JP2012084206A - Magnetic recording medium, magnetic reproducing device, magnetic reproducing method, and light modulation element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic disk in which tracks are formed by magnetic thin wires as data recording areas and which has no reproducing error regardless of the processing shape of the magnetic thin wires.SOLUTION: A magnetic disk includes magnetic thin wires 5 concentrically on a substrate, and a high Ms area 5s with relatively high saturation magnetization is locally provided for each magnetic thin wire 5 by ion implantation. Data of "0" or "1" is continuously recorded in the magnetic thin wires 5, and an area in which data is recorded moves through the magnetic thin wire 5 intermittently as magnetic domains D0, D1 or the like by pulse current supplied by a pair of electrodes 61, 62 which are connected to the both ends of the magnetic thin wire 5. A magnetic wall DW2 which reaches outside the high Ms area 5s by current supply spontaneously moves to a nearby high Ms area 5s and is locked when current is stopped in the pulse current. Therefore, minute positional displacement is corrected each time when the magnetic wall passes through the high Ms area 5s in the magnetic thin wire 5, so that the reproducing error can be prevented.

Description

  The present invention reads and reproduces data from a magnetic recording medium in which a track is formed of a magnetic material having a thin wire shape, and by supplying a current to the magnetic recording medium to move the domain wall in the track while sandwiching the domain wall. The present invention relates to a magnetic reproducing apparatus, a magnetic reproducing method, and an optical modulation element.

  In storage devices such as hard disk drives (HDD), with the increase in the amount of information to be handled, higher recording density and higher speed of recording and reproduction are being promoted. As the recording density is increased, the tracks of recording media such as magnetic disks used for HDDs are narrowed, and the length of one data (1 bit) in the track is shortened. In order to detect magnetism, the recording / reproducing system is a magnetic system using a magnetic head composed of a magnetoresistive element such as a GMR (Giant MagnetoResistance) element or a TMR (Tunnel MagnetoResistance) element, or A magneto-optical method using laser light irradiation is applied.

  Recording and reproduction on such a magnetic disk are carried out along the track (in the circumferential direction of the disk) by rotating the disk with a spindle motor and moving the magnetic head or the laser beam irradiation spot only in the radial direction of the disk. ) Magnetize (record) in a predetermined direction, or detect (reproduce) magnetism. In order to increase the speed of recording and reproduction in such a disc, firstly, the rotational speed of the disc is increased. However, there is a limit to increasing the rotational speed due to problems such as the time required for track magnetization during recording, the time required for magnetic detection during reproduction, and malfunctions due to disk vibration. Therefore, in an HDD or the like built in a personal computer, about 2 to 10 magnetic disks are stacked and each magnetic disk is provided with a magnetic head, and recording or reproduction is performed by recording or reproducing each magnetic disk in parallel. The playback speed can be increased.

US Pat. No. 6,834,005 JP 2010-20114 A

T. Koyama et al., “Control of Domain Wall Position by Electrical Current in Structured Co / Ni Wire with Perpendicular Magnetic Anisotropy”, Appl. Phys. Express 1, 101303 (2008) Xin Jiang et al., “Enhanced stochasticity of domain wall motion in magnetic racetracks due to dynamic pinning”, Nature Communications, 1, pp.1-5 (2010) T. Kato et al., “Planar patterned media fabricated by ion irradiation into CrPt3 ordered alloy films”, J. Appl. Phys. 105, 07C117 (2009)

  The recording and reproducing speed on the magnetic disk is converged to the length of 1 bit (bit length) on the track and the rotational speed of the disk. To further increase the speed, it is necessary to increase the number of disks to be recorded and reproduced simultaneously. For example, in order to realize a super high-definition (ultra high definition television) system, it is necessary to reproduce at a super high speed of about 72 Gbps. Even in a super high-definition system for experiments of about 24 Gbps, it is necessary to operate dozens of large-capacity storages for servers equipped with, for example, about 3 to 10 disks at the same time. I need. As described above, the recording medium and the reproducing apparatus thereof are not sufficiently capable of dealing with an increase in capacity and density of information to be handled.

  Here, as a method of moving recorded data without driving a recording medium, Patent Document 1 discloses that a thin line-shaped magnetic body (hereinafter referred to as a magnetic thin line as appropriate) is formed into a U-shape or the like and a track. A memory device is disclosed. This is because when a magnetic material is formed in a thin wire shape, magnetic domains are formed in the length direction, and when a current is further supplied in the length direction, all the domain walls generated so as to separate the magnetic domains are the length of the magnetic wire. This utilizes the characteristic of shifting in the same distance in the direction (see Non-Patent Documents 1 and 2). That is, each magnetic head for recording and reproduction is fixed to a predetermined location (a U-shaped top portion in Patent Document 1) on a track (magnetic wire), and a current is reversibly supplied from both ends of the track to provide a domain wall. The desired magnetic domain sandwiched between the magnetic heads is moved to a position facing the magnetic head. In this method, although it varies depending on the shape of the magnetic material (line width, etc.) and the supplied current, the moving speed of the domain wall is extremely high, from several tens m / s to about 250 m / s. Expected to exceed playback speed.

  In Patent Document 1, in order to enable rewriting of data by a random access method, wave-shaped magnetic wires in which a large number of U-shapes are connected in series are further provided in parallel, and a magnetic head is provided at each of the U-shaped top portions. It is set as the form provided with. Further, in Patent Document 2, magnetic thin wires having a simple configuration storing only one piece of data “1” and “0” per line are arranged in a matrix, and current is supplied to each magnetic thin wire. Thus, any data is selected. These technologies are suitable as a random access memory or a spatial light modulator that simultaneously presents a large amount of data, but are efficient as a recording medium that records and reproduces continuous data such as long-time moving images. Inferior. Accordingly, the present inventors have formed magnetic thin wires in a concentric shape and used this as a track in the same manner as a general magnetic disk or magneto-optical disk to form a disk-shaped recording medium (disk). With such a recording medium, it is not necessary to rotate the recording medium main body, so there is no malfunction due to vibration, and data can be moved on the track at high speed, so that recording and reproduction can be speeded up. .

  As described above, when a large number of data are recorded as magnetic domains continuously on one magnetic wire, a minute shift of the movement is accumulated in the shift movement of the domain wall by the current supply, that is, the movement of the data, leading to a reproduction error or the like. There is a fear. Therefore, since the domain wall generated in the magnetic thin wire has a characteristic that it is easily locked to the constricted portion or the bent portion of the magnetic thin wire, the magnetic wall is constricted (notch, figure) as in Patent Documents 1 and 2. 3 (b)) is formed, or as a bent shape, the domain wall is locked at a desired position in the magnetic fine wire to prevent displacement.

  However, if the configuration is such that the displacement of the magnetic thin wire is prevented, the strength of the force for locking the domain wall varies greatly depending on the constriction depth or the like, and high processing accuracy is required. Accordingly, the size (line width) is converged due to the processing limit of the magnetic thin wire, and the increase in recording density of the recording medium is restricted, so there is room for improvement in order to further increase the capacity. In addition, when such a magnetic wire is used as a light modulation element of a spatial light modulator, in addition to the processing accuracy, the light extraction efficiency is impaired due to light irregularly reflected at the constricted portion of the magnetic wire, which is also improved. There is room for.

  The present invention has been devised in view of the above problems, and is intended for a recording medium in which a track is formed with the magnetic fine wire, and has an even higher recording density as no reproduction error regardless of the processed shape of the magnetic fine wire. It is an object of the present invention to provide a magnetic recording medium that can be manufactured, and a magnetic reproducing apparatus and a magnetic reproducing method for reproducing such a magnetic recording medium at high speed. Another object of the present invention is to provide a light modulation element using a magnetic wire capable of suppressing light irregular reflection and improving light extraction efficiency.

  In order to solve the above problems, the present inventor, if there is a region with different saturation magnetization in the magnetic wire, when the magnetic wire is not supplied with current, the domain wall moves to a region with higher saturation magnetization in the region. We found out that it has a property, and came up with the idea of using a region with high saturation magnetization in the same way as the notches of current magnetic wires. And this inventor utilizes the phenomenon (refer nonpatent literature 3) that a saturation magnetization becomes low when a magnetic substance is ion-implanted, and provides a region | part with a high saturation magnetization locally in a magnetic fine wire, A method for locking in the region was found.

  A magnetic recording medium according to the present invention includes one or more magnetic fine wires formed by forming a magnetic material on a substrate in the form of fine wires, and binary data is applied to the magnetic fine wires as either of two different directions of magnetization. Recording is continuously performed in the thin wire direction of the magnetic thin wire, and a pulse current is supplied from one end of the magnetic thin wire to the other end in the thin wire direction, so that one of the binary data is recorded and formed in the magnetic thin wire. The domain wall generated between the magnetic domain and the magnetic domain formed by recording the other binary data moves intermittently in the thin line direction. In such a magnetic recording medium, the magnetic wire includes a high saturation magnetization region in a region partitioned in the direction of the thin wire as a region where the domain wall reaches when the current in the pulse current stops. Therefore, the magnetic fine wire is formed in advance by relatively increasing the saturation magnetization of the high saturation magnetization region when ions are implanted into other than the high saturation magnetization region.

  With such a configuration, the magnetic recording medium has the domain wall locked in the high saturation magnetization region at the time of stationary movement of the data recorded as the magnetic domain in the magnetic thin wire with the shift movement of the domain wall. The data shift is corrected when the current is stopped at, so that the data can be accurately reproduced even if the device for reproducing the data of the magnetic recording medium is not provided with a correcting means. In addition, since the high saturation magnetization region is formed by ion implantation, it can be easily formed at a desired position and size on the magnetic recording medium, the amount of change in saturation magnetization can be easily controlled, and the shape of the magnetic wire Therefore, the fine magnetic wires can be further miniaturized, and the recording density of the magnetic recording medium can be increased.

  Further, in the magnetic recording medium according to the present invention, it is preferable that the magnetic fine wires are formed concentrically with the substrate on the disk-shaped substrate, and the shape in plan view lacks a part of the ring. With this configuration, the magnetic recording medium has the same outer shape as a conventionally known recording medium, and even when the size of the magnetic recording medium is limited, the magnetic recording medium can be continuously long on the substrate without bending the magnetic wire. it can.

  Further, the magnetic fine wire of the magnetic recording medium according to the present invention may be formed of a magneto-optical material. With such a magnetic recording medium, reproduction can be performed by a magneto-optical method using laser light or the like.

  A magnetic reproducing apparatus according to the present invention is an apparatus for reproducing binary data recorded on the magnetic recording medium according to the present invention. The magnetic reproducing apparatus includes a selection unit that selects one or more magnetic wires from the magnetic recording medium, and a magnetic wall that is generated on the magnetic wire by connecting the magnetic wires selected by the selection unit at both ends. Current supply means for supplying a pulse current to be moved in the direction of the thin wire, magnetic detection means for detecting the magnetization direction in a region at a pre-designated position for detecting the magnetization direction of the magnetic thin wire, and the pulse current Data reproducing means for reproducing, as data, the magnetization direction detected by the magnetic detecting means when the current in the pulse current is stopped synchronously.

  Alternatively, in place of the magnetic detection means for detecting the magnetization direction of the magnetic thin wire, the magnetic recording is provided with light detection means for detecting the polarization direction of the light emitted from the magnetic thin wire, and the magnetic thin wire is formed of a magneto-optical material. A device for reproducing binary data recorded on a medium may be used. For this reason, in such a magnetic reproducing apparatus, the magnetic thin line is further provided with irradiation means for making light incident on the region of the designated position of the magnetic thin line selected by the selection means, and the light is emitted from the magnetic thin line. The data reproducing means reproduces the polarization direction of the light detected by the light detecting means as data instead of the magnetization direction of the magnetic thin wire.

  With this configuration, the magnetic reproducing apparatus automatically corrects the data shift when the current in the pulse current is stopped, so that it is possible to prevent a reproduction error without providing a correcting means or the like. Further, in the region at the position designated in advance for detecting the magnetization direction of the magnetic wire, the domain wall that is the boundary between the data does not always stop when the current is stopped, and one data reaches the entire region. Therefore, data is accurately reproduced by detecting magnetism or light from this area.

  The magnetic reproducing method according to the present invention is a method for reproducing binary data recorded on the magnetic recording medium, wherein a selection step of selecting one or more magnetic wires from the magnetic recording medium, and the selection A reproducing step of reproducing the data recorded on the magnetic thin wire. In this reproducing process, a current supply process for supplying a pulse current in the direction of the thin wire to the magnetic wire, which intermittently moves the domain wall generated in the magnetic wire, and a magnetization direction of the magnetic wire are detected. Magnetic detection processing for detecting a magnetization direction in a region at a position designated in advance, and reproducing the magnetization direction detected by the magnetic detection processing at the time of stopping the current in the pulse current as data in synchronization with the pulse current And a data reproduction process.

  Alternatively, as a method of reproducing binary data recorded on a magnetic recording medium in which a magnetic thin wire is formed of a magneto-optical material, the magnetic thin wire is emitted from the magnetic thin wire instead of the magnetic detection process for detecting the magnetization direction of the magnetic thin wire. Photodetection processing for detecting the direction of polarization of the emitted light may be performed. For this reason, in the reproducing step, an irradiation process is performed in which light is incident on the region of the designated position of the magnetic wire, and light is emitted from the magnetic wire. In such a magnetic reproduction method, in the data reproduction process, the polarization direction of the light detected in the light detection process is reproduced as data instead of the magnetization direction of the magnetic thin wire.

  By this procedure, when detecting magnetism or light, the domain wall that is the boundary between the data is locked in the highly saturated magnetization region of the magnetic wire, so that the region where only one data reaches is a region for detecting the magnetization direction In this case, magnetism or light can be detected from this area, and data can be accurately reproduced.

  The light modulation element according to the present invention includes a magnetic wire formed by forming a magneto-optical material in a thin line shape on a substrate, and a pair of electrodes connected to both ends of the magnetic wire, and is incident on the magnetic wire. The light is emitted while changing the direction of polarization of the light. In such a light modulation element, the magnetic fine wire has two or more magnetic domains formed continuously in the thin wire direction, and current is supplied in the thin wire direction through the pair of electrodes, thereby allowing two adjacent magnetic domains to be A domain wall generated between the magnetic domains moves in the direction of the thin line, and selectively causes one of the two magnetic domains to reach an incident region that is a region divided in the direction of the thin line where the light is incident. In such a light modulation element, the magnetic thin wire includes a high saturation magnetization region partitioned in a thin wire direction outside the incident region as a region where the magnetic domain wall reaches when the current is stopped. Therefore, the magnetic fine wire is formed in advance by relatively increasing the saturation magnetization of the high saturation magnetization region when ions are implanted into other than the high saturation magnetization region.

  With this configuration, since the domain wall is locked to the high saturation magnetization region provided outside the incident region in the magnetic thin wire when the current is stopped, the domain wall is not stopped in the light incident region, so that the operation is stable. .

According to the magnetic recording medium of the present invention, it is not necessary to perform processing such as constriction on the magnetic thin wire while maintaining high-speed reproduction, so that the capacity can be increased by further increasing the recording density.
According to the magnetic reproducing apparatus and the magnetic reproducing method according to the present invention, there is no data shift, and the data on the magnetic recording medium can be accurately reproduced at high speed.

  According to the light modulation element of the present invention, a spatial light modulator having a simple configuration can be obtained as a light modulation element including one magnetic body and a pair of electrodes connected thereto. In addition, since processing such as constriction or a bent portion is not performed on the magnetic fine wire, irregular reflection of light can be suppressed and light extraction efficiency can be improved.

1 is a schematic plan view illustrating a configuration of a magnetic recording medium according to the present invention. 1 is an external view showing a configuration of a magneto-optical magnetic reproducing apparatus according to the present invention. It is a top view explaining the structure of the magnetic fine wire in a magnetic recording medium, (a) is a schematic diagram of embodiment of this invention, (b) is a schematic diagram of a prior art example. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view in the length direction of a magnetic wire for explaining the configuration of a magnetic recording medium according to the present invention, (a) is a schematic diagram of a magnetic recording medium according to one embodiment, and (b) is another embodiment. It is a schematic diagram of the magnetic recording medium concerning. It is a graph which shows the change of the magneto-optic Kerr rotation angle with respect to the applied magnetic field in Fe film for demonstrating the relationship between the ion implantation to a magnetic body, and saturation magnetization, (a) is no ion implantation, (b) is Ga ion. The number 5.20 × 10 ¹⁰ / μm ² , (c) is the number of Ga ions 1.56 × 10 ¹¹ / μm ² . It is a schematic diagram for demonstrating the movement of the magnetic domain in the magnetic wire of the magnetic recording medium based on this invention, and is sectional drawing in the length direction of a magnetic wire. FIG. 2 is a cross-sectional view in the length direction of a magnetic wire for explaining a magnetic reproducing method according to the present invention, wherein (a) and (b) are methods using a magneto-optical magnetic reproducing apparatus, and (c) are magnetic methods. This is a method using a magnetic reproducing apparatus. FIG. 5 is an enlarged perspective view of a reproducing area of a magnetic recording medium for explaining a magnetic reproducing method according to a modification of the magneto-optical magnetic reproducing apparatus according to the present invention. It is a plane schematic diagram which shows the structure of the spatial light modulator provided with the light modulation element which concerns on this invention. It is a schematic diagram of the display apparatus using the spatial light modulator provided with the light modulation element which concerns on this invention, and is a figure corresponding to AA sectional drawing of FIG. It is a schematic diagram of the display apparatus using the spatial light modulator provided with another light modulation element which concerns on this invention, and is a figure corresponding to AA sectional drawing of FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for realizing a magnetic recording medium, a magnetic reproducing apparatus, and a magnetic reproducing method according to the present invention will be described with reference to the drawings.

[Magnetic disk]
As shown in FIG. 1, a magnetic disk (magnetic recording medium) 50 according to an embodiment of the present invention records data on a magnetic wire 5 formed by forming a magnetic material in a thin wire shape on a disk-shaped substrate 7 (see FIG. Storage) area. Binary data, that is, “0” or “1” data is continuously recorded in the magnetic thin wire 5 in the length direction of the magnetic thin wire 5 (hereinafter referred to as the thin wire direction). An area in which one piece of data of the magnetic thin wire 5 is recorded is referred to as one data area, and the length in the thin line direction is defined as a unit length. The recorded (stored) data is reproduced by mounting or incorporating the magnetic disk 50 in the magnetic reproducing apparatus 1, for example, as shown in FIG. In the magnetic wire 5, “0” and “1” data are recorded as either of two different directions of magnetization. Therefore, in the magnetic thin wire 5, there is one data area, or when data of the same value (either “0” or “1”) is continuously recorded, one magnetic domain is recorded in the continuous data area. Form. In this specification, the data area in the magnetic wire 5 will be described as a magnetic domain as appropriate.

  Since the magnetic thin wire 5 is supplied with current in the thin wire direction from one end to the other end thereof, all the domain walls that divide the magnetic domains in the magnetic thin wire 5 move by the same distance in the thin wire direction, so-called shift movement is performed. A series of data recorded in the magnetic domain, that is, the magnetic wire 5 moves sequentially. For example, by supplying a pulse current to the magnetic wire 5 by the magnetic reproducing apparatus 1, the data stored in the magnetic wire 5 moves intermittently with the domain wall without rotating the magnetic disk 50. Therefore, in the magnetic thin wire 5, a reproduction area 5r for detecting the magnetization direction and a recording area 5w for magnetizing in a direction corresponding to the data to be recorded are set to areas at predetermined positions on the magnetic disk 50, respectively. can do. The magnetic thin wire 5 includes a high Ms region (high saturation magnetization region) 5s having a relatively high saturation magnetization in a region partitioned in the thin wire direction as a region where the domain wall reaches when the current in the pulse current stops. As shown in FIG. 3A, the high Ms region 5 s is formed by implanting ions outside the region of the magnetic wire 5.

  As shown in FIG. 1, in the magnetic disk 50, the magnetic fine wires 5, 5,... Are concentrically formed on the substrate 7 with the insulating layer 8 interposed therebetween in a plan view. Specifically, one magnetic wire 5 is formed in a C-shape that lacks a part of an annulus in plan view, and the width (the length in the radial direction of the magnetic disk 50) and the thickness (film thickness) are constant. is there. Thus, in the present embodiment, the magnetic recording medium is called a magnetic disk 50 because the outer shape of the magnetic recording medium is based on a disk-shaped substrate and is similar to that of the current magnetic disk. Is similar to the shape of the track, which is the data recording area of the current magnetic disk, and is therefore referred to as the track 5 as appropriate. The number of the magnetic thin wires 5 formed on the magnetic disk 50 is not particularly limited, and may be set according to the track pitch (width and interval of the magnetic thin wires 5), the diameter of the magnetic disk 50, and the like. Further, the length in the length direction (track length) of each of the magnetic thin wires 5 in the magnetic disk 50 may not be the same length.

  Thus, the thin wire shape (planar shape) of the magnetic wire 5 is a straight line that is not bent or a sufficiently gentle curve with respect to the length in the thickness and width directions, and the outer shape is a disk shape as in this embodiment. In the case of the magnetic disk (magnetic recording medium) 50, an annular shape (arc) is preferable as a shape that can be made sufficiently long with respect to its outer dimensions and easy to manufacture. Such magnetic wires 5 can be made longer as they are formed closer to the outer periphery of the magnetic disk 50, and the area (capacity) in which data can be recorded can be increased as a whole of the magnetic disk 50. Further, the magnetic recording medium is not limited to a disk shape, and may be, for example, a plate having a rectangular shape in a plan view.

  A pair of electrodes 61 and 62 serving as connection terminals for supplying a current to the magnetic wire 5 from the outside of the magnetic disk 50 (for example, the magnetic reproducing device 1) are connected to both ends of the magnetic wire 5. The electrodes 61 and 62 are made of a general electrode metal material such as a metal such as Cu, Al, Au, Pt, or Ag, or an alloy thereof, and are laminated at both ends of each magnetic wire 5 in the magnetic disk 50. Connected. The electrodes 61 and 62 may be formed under the magnetic wire 5, and in that case, a part of the substrate 7 is removed so that it can be electrically connected to supply current from the outside. The electrodes 61 and 62 are exposed on the back surface (lower surface) of the magnetic disk 50. Alternatively, the electrodes 61 and 62 are formed so as to project outward from the end of the magnetic wire 5 in a plan view, penetrate the insulating layer 8 from the surface of the magnetic disk 50, and the upper surfaces of the electrodes 61 and 62. A contact hole that exposes the overhanging region may be formed.

(Magnetic wire)
In the magnetic disk 50, the magnetic wire 5 is formed on the substrate 7 via the insulating layer 8 as shown in FIG. 4, FIG. 6, and FIG. 7 show a cross section of the magnetic fine wire 5 by a surface along the fine wire direction. The magnetic wire 5 is made of a ferromagnetic material, and is preferably a perpendicular magnetic anisotropic material having magnetization in a direction perpendicular to the film surface. Specifically, a transition metal such as Ni, Fe, Co, or an alloy thereof, and further Pd, A laminated film of Pt and Cu can be mentioned. For materials reproduced by the magneto-optical method, a material (magneto-optic material) having a greater magneto-optic effect is preferable. The thickness of the magnetic wire 5 is 5 to 100 nm, the width is 10 to 200 nm, and the space between the magnetic wires 5 and 5 is preferably 40 to 200 nm. The shorter the width and interval, the more so-called track pitch (the sum of the width and interval of the magnetic wire 5). ) Is smaller, the recording capacity of the magnetic disk 50 can be increased. However, the magnetic wire 5 of the magnetic disk 50 has a width and a track pitch that can be adapted to the reproducing method. Specifically, in the case of a magneto-optical method using laser light, a width of about 100 nm or more is preferable. If it is a magnetic system by such a magnetoresistive effect element, about 60 nm or more in width is preferable. The fine wire direction length (track length) of the magnetic fine wire 5 is not particularly limited as long as it is sufficiently longer than the thickness and the length in the width direction. The magnetic thin wire 5 may be composed of an integral magnetic material for data storage (magnetization retention) and reproduction, but in order to record data, different materials are used as described later depending on the recording method. Need to be stacked. Therefore, the magnetic wire 5 is formed by stacking different materials in the recording area 5w (see FIG. 1) where data is recorded, or the entire magnetic wire 5 has the same configuration as the recording area 5w.

  The recording area 5w is an area for setting the magnetism of the magnetic wire 5 in the magnetization direction corresponding to the data in order to record data on the magnetic wire 5, and in this area, the structure of the magnetic wire 5 corresponds to the recording method. Shall be. The length of the recording area 5w in the direction of the thin line may correspond to the recording method and processing accuracy. Specifically, for example, as in the current recording method on a magnetic disk, as shown in FIG. 4A, when an external magnetic field is applied using a recording magnetic head 22 composed of magnetic poles as writing means, a magnetic thin wire is used. 5, a soft magnetic layer 51 is laminated via a nonmagnetic layer 52 under the head 5 (opposite the side facing the recording magnetic head 22). The soft magnetic layer 51 forms a magnetic path for the external magnetic field from the recording magnetic head 22 to form a perpendicular write magnetic flux with the magnetic wire 5. With such a configuration, for example, in FIG. 4A, in the initial state, the recording magnetic head 22 applies a downward magnetic field in the recording area 5w to the magnetic thin wire 5 in the upward direction, and magnetization is performed. Inverted downward.

  Further, since the magnetic disk 50 according to the present invention can record data on the entire magnetic wire 5 even if the position of the writing means is fixed with respect to the magnetic wire 5, the recording area 5w has the following configuration. You can also That is, the magnetic thin wire 5 has a spin-injection magnetization reversal element structure in the recording region 5w, the power source 22A capable of supplying a direct current by reversing the polarity of the direct current is used as the writing means, and the current is supplied to the recording region 5w. A desired magnetization direction can be obtained by spin injection magnetization reversal. Specifically, as shown in FIG. 4B, a magnetization fixed layer 54 is laminated on the magnetic wire 5 via an intermediate layer 53 made of a nonmagnetic material or an insulator, and an upper electrode 63 is further formed thereon. On the other hand, the lower electrode 64 is connected under the magnetic wire 5. The magnetization fixed layer 54 is made of a ferromagnetic material having a coercive force larger than the coercive force in the recording region 5w of the magnetic wire 5 and, if the magnetic wire 5 is a perpendicular magnetic anisotropic material, is also made of a perpendicular magnetic anisotropic material. The magnetization is fixed in one of the upward direction and the downward direction. Further, in order to reverse the spin injection magnetization in the recording area 5w of the magnetic fine wire 5, it is preferable that the thickness of the magnetic fine wire 5 is 5 to 30 nm for such a magnetic disk 50. In FIG. 4B, the substrate 7 and the insulating layer 8 (see FIG. 4A) are omitted. With such a configuration, the magnetic thin wire 5 becomes a magnetization free layer in the recording area 5w, the power source 22A is connected to the electrodes 63 and 64, and a current is supplied upward or downward corresponding to the data to be written. The magnetization can be in the same direction as the magnetization fixed layer 54 or in the opposite direction. For example, in FIG. 4B, a current is supplied downward from the upper electrode 63 to the lower electrode 64, and the magnetic thin wire 5 whose initial state is upward is fixed to the magnetization fixed layer 54 whose magnetization is fixed upward. The magnetization direction is reversed to the opposite direction.

  The reproduction area 5r is an area for detecting the magnetization direction of the magnetic wire 5. Specifically, when reproducing data on the magnetic disk 50, the magnetic domain (data area) reaching this area in the magnetic wire 5 is reproduced. This is a region where the magnetization direction is detected limited to the above. The reproduction region 5r has a length in the direction of a thin line corresponding to the reproduction method. Specifically, in the case of the magneto-optical method, although it depends on the wavelength of the laser beam, the length is preferably about 200 nm or more. If so, a length of about 20 nm or more is preferable. In addition, the reproduction area 5r is set to be equal to or less than the length (unit length Lb) of one data area (magnetic domain) of data stored in the magnetic thin line 5 to accurately detect the magnetization direction of the data area. This is preferable (see FIG. 7A). The magnetic thin wire 5 may have a structure corresponding to the reproducing method in the reproducing region 5r. For example, in the magneto-optical method, a material having a large magneto-optical effect may be laminated, or a reflective film may be provided below. (Not shown).

  In this embodiment, as shown in FIG. 1, the reproduction area 5r and the recording area 5w of all the tracks 5 are set at positions along the radius of a circle that is a planar view shape of the magnetic disk 50. However, the position is not limited to this, and may be a position along a straight line or a curve other than the radius. In any case, it is preferable that the reproduction areas 5r and 5r and the recording areas 5w and 5w in the adjacent tracks 5 and 5 are provided close to each other in all the tracks (magnetic thin wires) 5 of the magnetic disk 50. With this arrangement, for example, when data is reproduced by the magneto-optical magnetic reproducing apparatus 1 shown in FIG. 2, after the reproduction of the data of one track 5 is completed, the next, that is, the adjacent track 5 is reproduced. When shifting (seeking), the distance for moving the laser spot can be shortened to shorten the time. Therefore, in the magnetic disk 50 from which data is reproduced by the magnetic reproducing apparatus 1, the position of the reproducing area 5r is set to the moving path of the laser spot by the optical system 10 (mirror 14 and objective lens 15). Similarly, on the magnetic disk 50 from which data is reproduced and recorded by a magnetic magnetic reproducing apparatus or magnetic recording apparatus (not shown), the positions of the reproducing area 5r and the recording area 5w are set to the reproducing magnetic field. It is assumed that the head 21 (see FIG. 7C) and the recording magnetic head 22 (see FIG. 4A) are moved along the moving path.

  Further, in the present embodiment, as shown in FIG. 1, the track 5 has a playback area 5r in the front of the data (data area) moving direction (electrode 62 side) and a recording area 5w in the back (electrode 61 side). Each is provided. As will be described in detail later, in the magnetic disk 50 according to the present embodiment, the data region moves from the electrode 61 side to the electrode 62 side in one direction of the fine line direction by shift movement of the domain wall. Therefore, a large amount of data recorded in the recording area 5w can be stored in a long area in front of the recording area 5w. On the other hand, in the reproduction area 5r, a lot of data moving from the long area behind can be reproduced. Therefore, in the present embodiment, the reproduction area 5r and the recording area 5w are provided one by one apart from each other. However, the present invention is not limited to this. For example, a single area may be provided or adjacent to each other. When the recording area 5w is set at the same position or in the vicinity of the reproduction area 5r shown in FIG. 1, the data may be recorded in the reverse order with the data moving direction as the opposite direction. Further, one track 5 may be provided with a plurality of reproduction areas 5r and recording areas 5w, and the positions and number of these areas 5r and 5w are the magnetic reproduction apparatus 1 for reproducing the magnetic disk 50 (FIG. 2) and the like.

  A magnetic recording medium (magnetic disk) 50 according to the present invention includes at least one high Ms region 5s, which is a region in which saturation magnetization is higher than other regions, as shown in FIG. Provide. As will be described in detail later, the high Ms region 5s has the same effect as the constriction of the conventional magnetic wire 105 (see FIG. 3B) in the magnetic wire 5, and does not supply current to the magnetic wire 5. In the state, for example, when the pulse current is stopped, the domain wall is locked to the region 5s. Therefore, if the magnetic domain that moves together with the domain wall, that is, the data area is prevented from being displaced, and provided at a position spaced a predetermined distance from the reproduction area 5r in the fine line direction, one data area is always present when the pulse current is stopped. Since the control is performed so as to reach the position completely including the reproduction area 5r (see FIG. 7A), the data can be reproduced accurately. Such a high Ms region 5s can be formed by implanting ions into the magnetic wire 5 other than the region 5s. As the number of ions implanted into the magnetic wire 5 increases, the amount of decrease in saturation magnetization increases, the saturation magnetization of the high Ms region 5s where ions are not implanted relatively increases, and changes depending on the ion species and implantation conditions. . Examples of the ion species include Ga, N, O, Ar, Kr, and Xe. The saturation magnetization of the high Ms region 5s is not particularly limited, but is preferably about 1.2 to 10 times that of other regions so that the domain wall is suitably locked.

Next, the result of observing the change in saturation magnetization when ions are implanted into the magnetic material will be described in detail. A sample was formed by applying pure Fe as a magnetic material, forming a film with a thickness of 100 nm on a Si substrate, and forming it in a cross shape by crossing two rectangles of width 50 μm × length 250 μm by photolithography. . Ga ions (Ga ⁺ ) were perpendicularly incident on the sample surface into a square area of about 10 μm square at the center of the cross shape, and the change in saturation magnetization of the magnetic material was measured. The ion irradiation conditions were an acceleration voltage: 31 kV and a current: 858 pA, whereby Ga ions were implanted at a rate of 1.73 × 10 ⁹ / μm ² · sec per area and time. The irradiation time was changed to 30 seconds (number of ions: 5.20 × 10 ¹⁰ / μm ² ), 90 seconds (number of ions: 1.56 × 10 ¹¹ / μm ² ), and 0 (no ion irradiation). Different types of samples were made.

  Two coils are arranged so that the sample is sandwiched from both sides, and an external magnetic field is applied to the Fe film perpendicularly to the film surface while changing its magnitude. Instead of measuring saturation magnetization, surface magneto-optic Kerr effect measurement The Kerr rotation angle in the Ga ion irradiation region was measured with an apparatus (SMOKE). FIG. 5 shows a graph of the dependence of the Kerr rotation angle on the applied magnetic field. As described below, the rate of change in saturation magnetization can be calculated by comparing the amount of change in the Kerr rotation angle due to the applied magnetic field.

Assuming that the relationship of H⊥M holds for the change in the magnetization M due to the magnetic field H in the magnetic material, the effective magnetic field H _eff is the reaction applied to the magnetic material with respect to the external magnetic field H _ex applied to the magnetic material. Considering the magnitude of the magnetic field, it is expressed as (H _ex −NM / μ ₀ ). μ ₀ is the magnetic permeability of the vacuum and is a constant. N is a demagnetizing factor, but since the film thickness is extremely small with respect to the area of the sample, it can be regarded as approximately 1 (N≈1) when a magnetic field is applied perpendicularly to the sample. Further, the magnetization M of the ferromagnetic material can be regarded as a substantially saturated magnetic field Ms. Therefore, (H _eff ≈H _ex −Ms / μ ₀ ) is established.

  As shown in FIGS. 5A, 5B, and 5C, the Kerr rotation angle per magnetic field applied to the Fe film is increased by Ga ion implantation. In other words, the external magnetic field required to obtain the same Kerr rotation angle is reduced, which indicates that the saturation magnetization Ms in the Ga ion irradiation region is reduced. Therefore, the rate of change of the ratio of the sample after Ga ion implantation to the ratio of the external magnetic field / Kerr rotation angle of the sample before ion implantation (FIG. 5A) becomes the rate of change of the saturation magnetization Ms. Specifically, the saturation magnetization decreases to 62% before ion implantation when the irradiation time is 30 seconds in FIG. 5B, and 60 before ion implantation when the irradiation time is 90 seconds in FIG. 5C. It can be said that it fell to%. Note that even when the irradiation time is set to 90 seconds with respect to 30 seconds, the difference in the amount of decrease in saturation magnetization is small, and even if the irradiation time is extended, no decrease in saturation magnetization is confirmed. Presumed to deteriorate. Depending on ion irradiation conditions, ion species, magnetic material, etc., the saturation magnetization can be further reduced, and the saturation magnetization can be almost zero (see Non-Patent Document 3). However, if the saturation magnetization of the region other than the high Ms region 5s, that is, most of the magnetic wire 5 is extremely lowered, the magnetization of the data region is not retained and reproduction becomes difficult. The injection is controlled within a range that does not hinder regeneration.

[Method of manufacturing magnetic disk]
The magnetic disk 50 shown in FIGS. 1 and 4 can be manufactured, for example, by forming magnetic thin wires (tracks) 5 by a damascene method as shown below. First, an insulating film such as SiO ₂ or Al ₂ O ₃ is formed on a substrate 7 made of a known substrate material such as a Si substrate or a glass substrate whose surface is thermally oxidized by a known method such as a sputtering method. The insulating film 8 is formed by forming grooves in the shape of magnetic thin wires 5, 5,... By etching such as electron beam lithography and ion milling or reactive ion etching (RIE). After a magnetic material is deposited on the insulating layer 8 in a groove by a film forming method such as a sputtering method, the surface is removed of the magnetic material other than the groove by CMP (Chemical Mechanical Polishing) or the like. Magnetic thin wires 5, 5,. When different materials are laminated on the recording area 5w of the magnetic thin wire 5 or the like, the film is continuously formed before or after the magnetic material. Then, a mask is formed in the region to be the high Ms region 5s, and ions are irradiated on the magnetic thin wire 5 by using a mask by irradiating ions with an ion implantation apparatus applied to the manufacture of a semiconductor device, for example. An unimplanted high Ms region 5s is formed. It should be noted that the ions may be implanted into the insulating layer 8 between the magnetic thin wires 5 and 5, so that the mask may be a single line shared by all the magnetic thin wires 5. On both ends of the magnetic wire 5, an electrode metal material is formed by sputtering or the like, processed by photolithography and etching, or lift-off or the like to form electrodes 61 and 62. Finally, except for the electrodes 61 and 62, the surface is covered with a resin or the like (not shown). In forming the magnetic wire 5, the magnetic wire 5 is formed by a lift-off method after forming an insulating film (insulating layer 8) as a base, and then insulated between the magnetic wires 5 and 5. Layer 8 may be deposited. Alternatively, the high Ms region 5s may be formed in the magnetic wire 5 after the electrodes 61 and 62 are formed.

[Movement of magnetic domain wall in magnetic wire]
With reference to FIG. 6, the operation of the magnetic wall movement of the magnetic recording medium (magnetic disk) according to the present invention in the magnetic thin wire will be described. In the present invention, in order to reproduce the data recorded on the magnetic recording medium, the domain wall generated so as to sandwich the magnetic domain formed by recording the data on the magnetic thin line is moved in the direction of the thin line as follows. .

  In this embodiment, the magnetic wire 5 is made of a perpendicular magnetic anisotropic material, and its magnetization direction indicates up or down. Therefore, data “0” is downward magnetization, and “1” is upward magnetization. Is recorded. In the magnetic thin wire 5 shown in FIG. 6, two pieces of data “0” and “1” having a predetermined unit length Lb are continuously recorded. The “length” refers to the length (longitudinal direction) of the magnetic wire 5 unless otherwise specified, and this direction will be described as the front-rear direction (right and left in FIG. 6). At this time, as shown in FIG. 6 (a), the magnetic domain D0, which is the data area in which the data “0” is recorded, and the subsequent data “1” (on the left side in FIG. 6) are recorded. There is a magnetic domain D1, which is a data area that has been set.

In the magnetic material, domain walls are generated in adjacent magnetic sections such as between the magnetic domains D0 and D1 so as to divide both magnetic domains. In other words, each magnetic domain is sandwiched between domain walls, and in the magnetic wire 5, the domain D0 is formed between the domain walls DW1-DW2, and the domain D1 is formed between the domain walls DW2-DW3. Inside the domain wall, the magnetization gradually changes, that is, rotates from the magnetization direction of one of the two magnetic domains sandwiching it to the magnetization direction of the other magnetic domain. In general, the length (thickness) of the domain wall is about 5 to 100 nm and very short (narrow) with respect to the magnetic domain, although it depends on the width and thickness of the magnetic wire and the data length. Shows the domain wall schematically enlarged. Accordingly, the lengths L _D0 and L _D1 of the magnetic domains D0 and D1 are shown as having no domain walls DW1, DW2 and DW3 (which are 0). In FIG. 6A, L _D0 = L _D1 = Lb.

The cross-sectional area of the magnetic wire 5 is S, the saturation magnetization is Ms, and the magnetic moment of the data region in which the data “0” and “1” of the unit length Lb are recorded, that is, the magnetic domains D0 and D1, is represented by + m and −m. Then, the relationship of the following formula (1) is established. In the magnetic material, the magnetic moment of each magnetic domain is preserved in both direction and size unless a magnetic field is applied from the outside of the magnetic material.

  As shown in FIG. 6A, current is supplied to the magnetic thin wire 5 in the backward direction (left direction in FIG. 6) by the electrodes 61 and 62 at both ends thereof, and electrons are injected in the forward direction. Specifically, for example, the current supply unit 30 (see FIG. 2) of the magnetic reproducing apparatus 1 sets the electrode 61 to “−” and the electrode 62 to “+”, thereby supplying the current I from the electrode 62 to the electrode 61. . Then, under the influence of the electron spin torque, the domain walls DW1, DW2, and DW3 respectively move forward (right in FIG. 6) to the state shown in FIG. FIG. 6 (a) → (b)). Accordingly, the magnetic domains D0 and D1 sandwiched between these domain walls DW1, DW2, and DW3 also move forward.

The current density of the supplied current I is J, and the moving distance of the domain wall when the current I is supplied for a unit time Δt is Δl. At this time, the change amount Δm (= | −m − (+ m) |) of the magnetic moment before and after the domain wall DW2 between the magnetic domains D0 and D1 moves is reversed because the magnetization direction is reversed because the domain wall DW2 has passed. 2).

On the other hand, the number n _e of electrons injected into the magnetic nanowire 5 by the unit time Δt supply current I can be represented by the following formula (3). In the equation, e is an elementary charge (e≈1.6 × 10 ⁻¹⁹ C).

From the equation (3), the change Δm of the magnetic moment due to the current supply can be expressed by the following equation (4) because the magnetization direction is reversed when the spin polarizability of the magnetic wire 5 is p. Μ _B in the equation is a Bohr magneton.

(2 μ _B / e) is a constant, and the spin polarizability p and the cross-sectional area S are determined by the material, width and thickness of the magnetic wire 5, respectively. Therefore, the change amount Δm of the magnetic moment in the magnetic wire 5 depends on the current density J, and the moving distance Δl of the domain wall DW2 also depends on the current density J from the equation (2).

Further, the moving speed (domain wall speed) v of the domain wall DW2 can be represented by (Δl / Δt). Here, when the relationship of the following equation (5) is established from the equations (2) and (4), and this is further transformed, the domain wall velocity v can be expressed by the following equation (6).

From equation (6), the moving speed v of the domain wall DW2 when the constant current I is supplied to the magnetic wire 5 is constant. Accordingly, as shown in FIGS. 6A to 6B, the domain walls DW2 and DW3 move at the same domain wall speed v, that is, the movement distance is the same, and therefore the domain D1 sandwiched between these domain walls DW2 and DW3 is also , The same distance is moved, and the length L _D1 does not change (L _D1 = Lb). In this way, in the magnetic wire 5 having a uniform width and thickness, all the magnetic domains as the data area can be moved by an arbitrary distance by controlling the time for supplying a constant current. It is possible (see Non-Patent Document 1).

Next, the movement of the domain wall DW1 in FIGS. 6 (a) → (b) will be described. In FIG. 6A, the magnetic wire 5 has a high saturation magnetization relatively higher than the saturation magnetization Ms of the other region in the magnetic wire 5 in front of the domain wall movement direction of the magnetic domain D0 (hereinafter simply referred to as the front). An Ms region 5s is provided. Specifically, the saturation magnetization of the high Ms region 5s is βMs. Note that β is a constant (β> 1). The length Ls of the high Ms region 5s is sufficiently smaller than the data unit length Lb. 6A to 6B, the domain wall DW1 moves in the high Ms region 5s. From the above equation (6), the domain wall velocity due to the constant current supply in the magnetic material is inversely proportional to the saturation magnetization of the magnetic material. Therefore, the moving speed of the domain wall DW1 in the high Ms region 5s can be expressed by (v / β), which is 1 / β slower than the moving speed v of the domain walls DW2 and DW3 moving simultaneously in the magnetic wire 5. . The moving speed of the domain wall DW1 when moving in the high Ms region 5s is assumed to be v _Low (= v / β).

In FIG. 6 (a) → (b), the magnetic domain D0 sandwiched between the domain walls DW1 and DW2 moves at the domain wall speed V while the domain wall DW2 at the rear moves, while the domain domain speed at the front domain wall DW1 is lower than that. Since it moves at v _Low , its length L _D0 contracts while moving together. The contracted length L _D0 when the magnetic domain D0 reaches the high Ms region 5s and includes part or all of it is as follows. It is assumed that the ratio x (0 <x ≦ 1) of the length Ls of the high Ms region 5s is included in the magnetic domain D0. When x = 1, the magnetic domain D0 includes the entire high Ms region 5s. That is, the length (x × Ls) of the magnetic domain D0 exists in the high Ms region 5s of the saturation magnetization βMs, and the other length exists in the region of the saturation magnetization Ms. In the high Ms region 5s, the cross-sectional area is the same S, and the magnetic moment m of the magnetic domain D0 is preserved and constant as described above, and therefore exists outside the high Ms region 5s according to the equation (1). The length of the magnetic domain D0 is (Lb−x × Ls × β). Therefore, the length L _D0 of the magnetic domain D0 can be expressed by the following equation (7) when the magnetic domain D0 reaches the high Ms region 5s.

When the current I is further supplied, the domain walls DW1, DW2, and DW3 move further forward as shown in FIGS. 6 (b) → (c) → (d). At this time, since the domain wall DW1 passes through the high Ms region 5s and moves at the same domain wall speed v as the domain wall DW2, the domain D0 maintains the contracted state and moves to the right. Then, at the stage of FIG. 6D, the domain wall DW2 reaches the high Ms region 5s. Therefore, when the current I is further supplied, as shown in FIGS. 6D to 6E, the domain wall DW2 moves in the high Ms region 5s at the domain wall velocity v _Low , while the domain walls DW1 and DW3 are domain wall velocity v. Move with. As a result, as shown in the upper part of FIG. 6E, the magnetic domain D1 is contracted, while the magnetic domain D0 is expanded and its length L _D0 is restored (L _D0 = Lb).

  As described above, even if a single magnetic fine wire 5 is provided with a region (high Ms region 5s) having different saturation magnetization in a region partitioned in the thin wire direction, the moving speed of the domain wall is increased according to the change of saturation magnetization. Since the magnetic domain changes and the magnetic domain expands and contracts in the direction of the fine line, the domain wall as a whole holds the shift movement. Therefore, the movement speed of the data area at a specific position of the magnetic wire 5 by constant current supply is constant.

Next, the operation of the magnetic wire 5 when the supplied current is stopped will be described. In the upper part of FIG. 6 (e), the domain wall DW2 reaches the interface inside and outside the high Ms region 5s immediately before leaving the high Ms region 5s. In the vicinity of the interface, a gradient is formed in which the saturation magnetization of the magnetic fine wire 5 gradually decreases along the fine line direction from βMs in the high Ms region 5s to Ms outside the high Ms region 5s. As described above, in the domain wall, the magnetization gradually rotates from one magnetization direction of the two magnetic domains sandwiching the domain wall to the magnetization direction of the other magnetic domain. Then, in the domain wall of the magnetic wire 5 where the current is stopped (no electrons are injected), the magnetization tends to rotate as close as possible to the upper or lower direction, which is the easy axis of magnetization. However, since the magnetization is different in the upward and downward directions on both sides of the domain wall, the magnetizations in the vicinity of both sides tend to rotate in opposite directions, and usually the magnetization rotates. The domain wall is stationary by maintaining the equilibrium without any problems. As for the domain wall DW2 in the upper stage of FIG. 6E, when the magnetizations in the regions in the vicinity of the magnetic domains D0 and D1 on both sides (front and rear) are compared, the magnetization near the rear magnetic domain D1 has higher saturation magnetization. Hard to rotate. Therefore, when the current is stopped, the domain wall DW2 moves from the magnetic domain D0 side to the magnetic domain D1 side by rotating the magnetization close to the magnetic domain D0, which is more easily rotated, to the same downward direction as the magnetic domain D0. Move (reverse) in the opposite direction. The movement of the domain wall in a state where the current supply is stopped is referred to as “voluntary movement”. Then, when the domain wall DW2 reaches the central portion of the high Ms region 5s where the saturation magnetizations on both sides are equal to βMs, the magnetization is balanced and stationary without rotating (lower stage in FIG. 6 (e)). In accordance with the stationary position of the domain wall DW2, the domain walls DW1 and DW3 also have lengths L _D0 and L _D1 (refer to the equation (7)) in which the magnetic domains D0 and D1 hold the respective magnetic moments + m and −m. Move (retreat) and then stop.

  As described above, when the high Ms region 5s, which is a region having a high local saturation magnetization divided in the thin line direction, is provided in the magnetic thin wire 5, the current is stopped in a state where the domain wall reaches the interface inside and outside the high Ms region 5s. In this case, the domain wall moves spontaneously so as to be locked to the high Ms region 5s and then stops. Then, in accordance with the spontaneous movement of the domain wall, other domain walls also move, that is, shift movement is performed. The spontaneous movement of the domain wall is not limited to the backward movement as shown in FIG. 6 (e). For example, as shown in FIG. 6 (a), the domain wall DW1 starts to enter the high Ms region 5s. Is stopped, the domain wall DW1 spontaneously moves forward and is locked in the high Ms region 5s. Further, as shown in FIG. 6C, even if the current is stopped in a state where the domain wall DW2 is sufficiently separated from the high Ms region 5s, the saturation magnetization on both sides is balanced by Ms. Do not move.

  The domain wall spontaneously moves only in a region where the saturation magnetization around the interface inside and outside the high Ms region 5s forms a gradient. In such a region, the domain wall moves toward the higher saturation magnetization, and the high Ms region It reaches a region without a gradient of saturation magnetization in 5 s and stops still. Therefore, in order to control the position where the domain wall is locked more accurately, the length Ls of the high Ms region 5s in the fine line direction is not less than the domain wall length (thickness) and not too long with respect to the domain wall. Specifically, it is preferably 1 to 10 times, which corresponds to about 1/10 to 2 times the width of the magnetic wire 5 and is in the range of about 10 to 500 nm. Further, the saturation magnetization of the high Ms region 5s is not saturated when the difference from other regions is small and the saturation magnetization gradient near the interface is insufficient and the domain wall does not move spontaneously. The gradient of magnetization becomes steep, and there is a possibility that it is difficult to exit from the high Ms region 5 s in the movement of the domain wall due to current supply, and it is necessary to increase the current density J. Therefore, the saturation magnetization of the high Ms region 5s is about 1.2 to 10 times the saturation magnetization of the other regions as described above so that the magnetic wall 5 (data region) is preferably moved by the pulse current. Set the range.

As described above, in the magnetic wire 5, the magnetic domain, that is, the data area moves along the thin wire direction when current is supplied to the magnetic wire 5, so that the data continuously stored in the thin wire direction is The reproduction area 5r is switched in order. And it is possible to move an arbitrary distance by controlling the time for supplying the current. Therefore, a pulse current having a pulse width t _H (t _H = Lb / v) as a time for moving the distance of the unit length Lb outside the high Ms region 5s (region having the saturation magnetization Ms) as the magnetic wire 5 , The data area can be shifted and shifted in increments of unit length Lb, that is, one data at a time. Then, by providing the magnetic thin wire 5 with the high Ms region 5s that is a region partitioned in the thin wire direction, the domain wall that has reached the position shifted from the high Ms region 5s immediately before stopping the current in the pulse current is the high Ms region. It spontaneously moves up to 5 s and is locked, and the entire data area of the magnetic wire 5 is shifted in accordance with this movement. Accordingly, every time the switching between “0” and “1” in the series of data recorded on the magnetic wire 5, that is, the domain wall passes through the high Ms region 5 s, a minute positional shift of the data region is corrected. Therefore, the position of the data area does not shift so much that the magnetic thin wire 5 cannot be corrected. Then, in the magnetic wire 5, the domain wall is locked in the high Ms region 5 s when the current is stopped, so that in other regions of the magnetic wire 5, a region where the domain wall does not always reach when the current is stopped is formed. . By setting such an area as the reproduction area 5r, it is possible to easily control so that one of the data areas always reaches the entire reproduction area 5r when the current in the pulse current is stopped.

  For example, as shown in FIG. 7A, the current is stopped by providing a high Ms region 5s behind (left in FIG. 7) a distance of one data region (unit length Lb) from the reproduction region 5r. Sometimes, the position of the domain wall DW between the (m + 1) th data area and the (m + 2) th data area is corrected in the high Ms area 5s, so that the mth data area reaches the reproduction area 5r with high accuracy. To do. Although the reproduction area 5r needs to have at least a length corresponding to the reproduction method of the magnetic disk (magnetic recording medium) 50, it is not necessary to further increase the unit length Lb by providing a margin for the positional deviation of the data area. Therefore, the data can be stored by shortening the unit length Lb to near the reproduction area 5r. As a result, the capacity of the magnetic disk (magnetic recording medium) 50 can be increased. Note that the interval between the reproduction area 5r and the high Ms area 5s is not particularly defined as long as the position of the data area at rest can be controlled, and is preferably set to an interval from 0 to several data areas. For example, as shown in FIG. 7C, when the reproduction area 5r is set to an area that straddles two consecutive data areas, the boundary (domain wall) between these data areas reaches the center of the reproduction area 5r. The position of the high Ms region 5s is set so as to be stationary. In the magnetic thin wire 5, two or more high Ms regions 5s may be formed, or may be formed at a location away from the reproduction region 5r, for example, in the vicinity of the recording region 5w.

  The locking effect of the domain wall of the high Ms region 5s in the magnetic wire 5 is due to the saturation magnetization gradient around the interface inside and outside of the high Ms region 5s, so that the magnetic wire 5 is all outside the high Ms region 5s. It is not necessary to lower the saturation magnetization by implanting ions into this region. As shown in FIG. 7B, by forming the two low Ms regions 5e, 5e with an interval of the thin line direction length Ls, the region sandwiched between the low Ms regions 5e, 5e The high Ms region 5s has a relatively high saturation magnetization with respect to the vicinity of. In the case where it is not desirable to reduce the saturation magnetization by ion implantation to almost the entire area other than the portion where the magnetic domain wall is locked due to the magnetic characteristics of the magnetic material forming the magnetic thin wire 5, the magnetic material is divided in the thin wire direction in this way. Low Ms regions 5e and 5e, which are limited regions, may be formed. As described with reference to FIG. 6, the magnetic domain contracts in the high saturation magnetization region. On the contrary, the data region reaching the low Ms region 5e expands.

  The length in the thin line direction of the low Ms region 5e is shorter than the unit length Lb in FIG. 7B and sufficiently shorter than the extended data region, but may be longer than the extended data region. Not specified. However, since the saturation magnetization is also gradient near the interface of the low Ms region 5e that is not adjacent to the high Ms region 5s, the inside of the low Ms region 5e is particularly close to the inside of the low Ms region 5e when the current is stopped. If the magnetic domain wall has reached, the magnetic domain wall tends to spontaneously move out of the low Ms region 5e. For example, if the length of the low Ms region 5e is about the same as that of the extended data region, one domain wall reaches the inner side of one interface of the low Ms region 5e when the current stops, and at the same time, the other interface There is a case where another domain wall has reached the outer side. Even if the domain wall near the interface moves out of the low Ms region 5e, the domain wall near the interface tries to remain stationary at this location, and the spontaneous movement of the two domain walls conflicts with each other. The domain wall locking effect becomes unstable, such as being influenced by a minute difference in the degree of the gradient of Therefore, for example, the interface on the side not adjacent to the high Ms region 5s of the low Ms region 5e is sufficiently separated from the position where the domain wall has reached when the current is stopped so that the two or more domain walls do not spontaneously move against each other. It is desirable to design such that

The current stop time t _L in the pulse current may be set to be equal to or longer than the time required to detect the magnetization direction in accordance with the reproduction method. The magnitude of the current | I | is set based on the width and thickness of the magnetic wire 5 and the reproduction speed because the domain wall velocity v increases as the current density J per cross-sectional area S of the magnetic wire 5 increases. In order to supply current in a constant direction opposite to the domain wall moving direction, either positive or negative direct current is used. Specifically, it is preferable to adjust the current density J: 10 ⁵ to 10 ¹³ A / m ² , the pulse width t _H : 1 ps to 10 μs, and the stop time t _L : 10 ps to 10 μs. In addition, in order to move the data area by one data length Lb, the current is intermittently moved by stopping the current by not only supplying the current once per time of the pulse width t _H but also by supplying the current twice or more times. You may let them.

Even when data is recorded on the magnetic recording medium, data can be continuously recorded in the direction of the thin wire of the magnetic wire by supplying a pulse current to the magnetic wire in the direction of the thin wire, as in reproduction. In FIG. 4, the magnetization direction in the initial state of the magnetic wire 5 is upward, which is a state in which “1” is recorded as initial data. By recording data “0” different from the initial data “1” on the magnetic thin wire 5, a downward magnetic domain is formed in the recording area 5 w as shown in FIGS. Domain walls DW and DW sandwiching the magnetic domain are generated. Therefore, by supplying the current for the time of the pulse width t _H after recording, the area where the data “0” is recorded is shifted by the distance of the unit length Lb together with the domain wall DW. The area can reach the recording area 5w. In the data recording, the current stop time t _L in the pulse current may be set to be equal to or longer than the time required for magnetization (magnetization reversal) in the desired direction of the magnetic wire 5 corresponding to the recording method. Here, the recording area 5w is longer in the fine line direction than the unit length Lb. Accordingly, a part of the data area (magnetic domain) in which data is recorded immediately before remains in the recording area 5w. By recording the next data in the recording area 5w, the length of the data area becomes the unit length Lb. Shortened to Thus, regardless of the length of the recording area 5w, a data area to be recorded is stored in the unit length Lb which corresponds to the pulse width t _H of the pulse current. Also, when data is recorded, the unit length Lb may be moved by supplying the current twice or more times.

  As described above, in the magnetic recording medium according to the present invention, a region having a high saturation magnetization is locally formed in a magnetic thin wire by ion implantation, and this region is formed by processing the magnetic thin wire (FIG. 3 ( b) has the same effect of locking the magnetic domain walls as in the case of (b), and can prevent malfunction due to data shift in the magnetic wire during data reproduction or the like.

  Next, an embodiment of a magnetic reproducing apparatus and a magnetic reproducing method for reproducing data recorded on the magnetic recording medium according to the present invention will be described.

[Magnetic reproduction device: magneto-optical method]
A magnetic reproducing apparatus according to the present invention will be described with reference to FIG. The magnetic reproducing apparatus 1 is an apparatus that mounts a magnetic disk (magnetic recording medium) 50 (see FIG. 1) according to the present invention and reproduces data recorded on the magnetic disk 50 by a magneto-optical method. The magnetic reproducing apparatus 1 further includes an optical system (irradiation means) 10 that irradiates incident light onto a predetermined region on the surface (upper surface) of the magnetic disk 50, and the polarization direction of the emitted light that is reflected by the magnetic disk 50. A detection unit (light detection unit) 20 for detecting the current, a current supply unit (current supply unit) 30 for supplying a pulse current to the track (magnetic thin wire) 5 of the magnetic disk 50, and a control unit (selection unit, Data reproducing means) 40.

  The magnetic reproducing apparatus 1 makes light incident on the track 5 of the magnetic disk 50 in the same way as the reproduction of the magnetic disk (magneto-optical disk) by the current magneto-optical system, and this light is magnetized in the direction of magnetization of the track 5 by the magneto-optic effect. The data is reproduced by detecting the direction of the polarization of the light (outgoing light) reflected and emitted by rotating (rotating) the direction of the polarization correspondingly. Therefore, the optical system 10 and the detection unit 20 can have the same configuration as that applied to the current magneto-optical magnetic reproducing apparatus. However, unlike the current magnetic reproducing apparatus, the magnetic reproducing apparatus 1 does not require a magnetic disk rotational drive mechanism such as a spindle motor, and is provided with a current supply unit 30 instead. Further, in the magnetic reproducing apparatus 1, the magnetic disk 50 may be replaceable as in a current DVD (Digital Versatile Disc) reproducing apparatus, or may be built in as in an existing HDD apparatus. In the present embodiment, the surface (upper surface) of the magnetic disk 50 is the light incident / emission surface, and the upper side is the light incident / emission direction.

  The optical system 10 includes a laser irradiation device 11 and one or more lenses (in FIG. 2, a lens group 12 including two lenses) that are optically connected to the laser irradiation device 11 and reduce or enlarge the laser light to a predetermined spot diameter. ), A polarizer (polarizing filter, not shown) that blocks polarized light in a specific direction, a half mirror 13 that further transmits light transmitted through the polarizer, and a mirror for irradiating a desired position on the surface of the magnetic disk 50 14 and an objective lens 15 for narrowing a light incident region (laser spot). On the other hand, the detection unit 20 includes an imaging device (not shown) that images emitted light reflected by the magnetic disk 50. The light emitted from the magnetic disk 50 is reflected by the half mirror 13, travels through an optical path different from the incident light, and enters the detection unit 20. The laser irradiation device 11 is a device that irradiates laser light having a predetermined wavelength (for example, 500 nm). The mirror 14 and the objective lens 15 are movable along the radial direction of the magnetic disk 50, and move the laser spot onto a predetermined area of the track 5 on which data to be reproduced is recorded. This predetermined region is a region at a position designated in advance for detecting the magnetization direction of the track (magnetic thin wire) 5. The region at a predesignated position for detecting the magnetization direction corresponds to the reproduction region 5r (see FIG. 1) from the embodiment of the magnetic recording medium (magnetic disk) 50, and the position is designated. This is a predetermined area where light is incident on the mounted or built-in magnetic disk 50. As described in the above embodiment (see FIGS. 7A and 7B), the reproduction region 5r always corresponds to the position of the high Ms region 5s, and the entire data is always displayed when the current to the magnetic wire 5 is stopped. It is set to an area where one of the areas has reached. As the imaging device of the detection unit 20, a light detector such as a CCD camera or a photodiode that can detect light and has a time resolution faster than the reproduction speed of one data can be applied.

  The current supply unit 30 is connected to electrodes 61 and 62 (see FIG. 1) provided at both ends of each magnetic wire (track) 5 of the magnetic disk 50 to supply a pulse current to the magnetic wire 5 in the direction of the wire. The current supply unit 30 includes, for example, terminals connected to the electrodes 61 and 62 of all the magnetic thin wires 5 of the magnetic disk 50 and switches for each terminal, and is limited to the magnetic thin wires 5 that supply a pulse current. Can be configured to be connected (not shown). Due to this pulse current, the magnetic domain, which is the data region, moves intermittently along the length direction of the magnetic wire 5 along the magnetic wall in the magnetic wire 5. Areas enter in order and exit. Therefore, the magnetic reproducing apparatus 1 does not require a mechanism for rotating and driving the magnetic disk 50 itself, and the optical system 10 only needs to be able to irradiate one spot for each track 5, that is, the reproducing area 5r. The control unit 40 selects the magnetic thin wire 5 for reproducing data from the magnetic disk 50, instructs the magnetic thin wire 5 to supply a pulse current to the current supply unit 30 according to the selected magnetic thin wire 5, and moves the mirror 14 and the like of the optical system 10 Let Further, the control unit 40 causes the detection unit 20 to detect the direction of polarization of the emitted light in synchronization with the period of the pulse current supplied by the current supply unit 30, and reproduces the direction of polarization as data.

[Magnetic reproduction method]
Next, a method for reproducing a magnetic disk by the magnetic reproducing apparatus (see FIG. 2) according to the present invention will be described. In the present embodiment, a description will be given assuming that an arbitrary track (magnetic thin line) is reproduced. In the magnetic reproducing method according to the present invention, the selection step and the reproducing step are repeated as necessary, and the direction of polarization of light emitted from the magnetic thin wire is detected by a magneto-optical method, and the direction of polarization is reproduced as data. To do.

(Selection process)
In the selection step, the control unit 40 selects one track 5 in which data to be reproduced in the subsequent reproduction step is stored from the tracks (magnetic thin lines) 5, 5,. For example, if the selected track 5 is the first selection step, the outermost track 5 of the magnetic disk 50 is selected, and if it is the second time or later, the track 5 reproduced in the immediately preceding reproduction step is selected. It may be set to select one on the inner peripheral side adjacent to. Alternatively, it may be set so that an arbitrary track 5 can be selected by an operation from the outside of the magnetic reproducing apparatus 1. When the track 5 from which data is to be reproduced is selected in the selection step, the control unit 40 moves the mirror 14 and the objective lens 15 of the optical system 10 so that the reproduction spot 5r of the track 5 is irradiated with the laser spot. To. Further, the control unit 40 connects the current supply unit 30 to the electrodes 61 and 62 of the track 5 so as to supply a pulse current to the track 5, and proceeds to the reproduction process.

(Regeneration process)
In the reproduction process, the current supply unit 30 supplies a pulse current to the track (magnetic thin line) 5 of the magnetic disk 50 selected in the selection process in the direction of the thin line, and moves the data area intermittently with the domain wall (current). Supply process), the optical system 10 irradiates the reproduction region 5r of the track 5 with a laser beam as polarized light in one direction (irradiation process). Then, the detection unit 20 detects the polarization direction of the outgoing light reflected by the track 5 (light detection process), and the control unit 40 determines whether the polarization direction of the outgoing light detected when the current in the pulse current is stopped is “0” or The data is converted into “1” data and reproduced (data reproduction process).

(Regeneration process: current supply processing)
The current supply unit 30 is connected to the electrodes 61 and 62 of the track 5, and supplies either positive or negative DC constant current and pulse current having a pulse period to the track 5. Due to this pulse current, the data area in the track 5 shifts and shifts intermittently. The movement of the data area is as described for the shift movement of the domain wall in the magnetic wire 5 of the magnetic disk 50 (see FIG. 6), and thus the description thereof is omitted.

(Regeneration process: irradiation treatment)
In the optical system 10, the laser light irradiated from the laser irradiation device 11 becomes parallel light having a predetermined spot diameter by the lens group 12, passes through a polarizer (not shown), and becomes incident light of light of one polarization component. . Further, the incident light passes through the half mirror 13, travels straight, is reflected by the mirror 14, is collected by the objective lens 15, and is irradiated toward the reproduction region 5 r of the selected track (magnetic thin wire) 5. Is done. The incident light is condensed by the objective lens 15, reduced in size to the size of the reproduction area 5 r, incident on the reproduction area 5 r of the magnetic wire 5, reflected, transmitted again through the objective lens 15, and emitted light. It becomes. Therefore, as shown in FIG. 7A, in the present embodiment, the reproduction region 5r is set to a length in the thin line direction that is equal to or larger than the spot diameter of laser light (incident light) that can be reduced in diameter by the objective lens 15.

(Regeneration process: light detection process)
The outgoing light travels in the opposite direction along the same optical path as the incident light and is reflected by the mirror 14. When the emitted light is reflected by the magnetic wire 5, the direction of polarization is rotated (rotated) by the magneto-optic Kerr effect. Further, the rotations are opposite to each other depending on whether the magnetization direction of the reflected (irradiated) region of the magnetic wire 5 is upward or downward. That is, the direction of polarization of the emitted light differs depending on the magnetization direction of the magnetic wire 5 in the reproduction region 5r. Therefore, by detecting the direction of polarization of the emitted light by the detection unit 20, the data area (the mth in FIGS. 7A and 7B) that has reached the reproduction area 5r of the magnetic wire 5 at the time of reflection. It is possible to determine whether the data area is a magnetic domain in which the magnetization direction is downward or upward, that is, which data “0” or “1” is recorded. As a method for detecting the direction of polarized light, a differential method applied to reproduction by a known magneto-optical method can be mentioned. Further, a polarizer (not shown) different from that provided in the optical system 10 is disposed on the optical path of the emitted light (for example, between the half mirror 13 and the detection unit 20), and the optical rotation is performed in one direction. It may be configured such that only the emitted light is blocked by the polarizer and does not enter the detection unit 20.

(Reproduction process: Data reproduction process)
The detection unit 20 captures (detects) the irradiated outgoing light by photoelectric conversion at the timing when the data region is stationary in the magnetic wire 5, that is, when the current supply unit 30 stops the current in the pulse current. At this time, the control unit 40 controls the current supply unit 30 and the detection unit 20 to match the timing of imaging by the detection unit 20. The control unit 40 recognizes the reproduction data as “0” or “1” depending on whether the detection unit 20 captures light or not, and converts it into a signal, and converts the obtained signal to the outside of the magnetic reproduction device 1. To be reproduced as information such as video and audio.

  As described above, the magnetic reproducing apparatus 1 detects the direction of polarization of light from the reproducing area 5r as a predetermined area while moving the data area in the track (magnetic thin wire) 5. When all the data stored in the track 5 is reproduced, the supply of the pulse current is stopped, the reproduction process is completed, and a new track 5 is selected again in the selection process. Further, when the reproduction of data of all the tracks 5 on the magnetic disk 50 is completed, the reproduction of the magnetic disk 50 is completed.

  As described above, according to the magnetic reproducing apparatus and the magnetic reproducing method according to the present invention, the magnetic wall is locked to the high Ms region 5s in the track (magnetic wire) 5 when the current is stopped in the pulse current of the current supply process. Thus, the minute displacement of the data area is automatically corrected (see FIG. 6E). For this reason, the data area is not misaligned so as to cause a reproduction error in the reproduction area 5r, and one data area always reaches the entire reproduction area 5r when the current is stopped, so that data can be reproduced accurately. .

(Modification of magnetic reproducing device)
In the magnetic reproducing apparatus 1, data is reproduced by selecting one track 5 from the magnetic disk 50, but one laser including a reproducing area 5 r of two or more adjacent tracks 5 on the magnetic disk 50. By irradiating the spot, data can be reproduced in parallel for these tracks 5. Here, as a modification, a magnetic reproducing apparatus that selects four adjacent tracks 5 from the magnetic disk 50 and simultaneously reproduces these data will be described with reference to FIG. In FIG. 8, in order to easily identify the optical paths of incident light and outgoing light (reflected light), the laser light is shown to be incident and emitted with an inclination, and mirrors and the like are omitted. Similar to the magnetic reproducing apparatus 1 shown in FIG. 2, the magnetic reproducing apparatus includes an optical system 10, a detection unit 20, a current supply unit 30, and a control unit 40. The configuration of the magnetic disk 50 is the same as that described above (see FIG. 1), but a series of data is recorded in parallel on each of the four tracks 5. In the present modification, in the optical system 10 (see FIG. 2), the objective lens 15 is not used, and the lens group 12 uses parallel light with a spot diameter that irradiates the magnetic disk 50 with laser light.

  In the magnetic reproducing method of this modification, the control unit 40 selects four adjacent tracks 5 in the selection process, and the current supply unit 30 moves these tracks 5 in the data area at the same timing in the current supply process. Then, the laser spot is irradiated from the optical system 10 to the area including the reproduction area 5r of the four tracks 5 by the irradiation process. The reflected light (emitted light) of the irradiated laser beam (parallel light) on the magnetic disk 50 includes data in the data areas of the four tracks 5. However, since the laser spot is circular, the emitted light includes data in the data area before and after the reproduction area 5r in each track 5. Therefore, the detection unit 20 detects the emission light from the reproduction region 5r by dividing the region where the emission light from the magnetic disk 50 is incident (detection region in FIG. 8). To signal. According to such a method, since it is sufficient to irradiate two or more adjacent tracks 5 with one laser beam, the magnetic reproducing apparatus only needs to have one optical system 10.

  Further, as described above, the minute displacement of the data area is automatically corrected by the high Ms area 5s formed on the track (magnetic thin wire) 5. Therefore, if the difference in data length between two or more tracks 5 to be reproduced in parallel is as small as, for example, an error at the time of recording, the data for all of these tracks 5 when the current is stopped in the pulse current. The area position is automatically aligned. Therefore, the current supply unit 30 supplies an independent pulse current to each of the tracks 5 selected at the same time, and it is not necessary to control the moving distance and moving speed of the data area for each track 5, thereby simplifying the structure. Specifically, the electrodes 61 and 62 of the track 5 to be reproduced in parallel with the current supply unit 30 may be connected in parallel to supply a common pulse current. If two or more tracks 5 are reproduced in parallel as described above, further high-density data can be reproduced without simultaneously operating a large number of magnetic reproducing apparatuses.

[Magnetic reproduction device: Magnetic system]
Another magnetic reproducing apparatus according to the present invention will be described. The same elements as those in the magneto-optical magnetic reproducing apparatus 1 (see FIG. 2) are denoted by the same reference numerals, and description thereof is omitted. A magnetic reproducing device (not shown) includes a magnetic disk (magnetic recording medium) 50, and magnetization in a reproducing area 5r, which is an area at a predesignated position for detecting the magnetization direction of the track (magnetic wire) 5. A detection unit (magnetic detection unit) 20A (see FIG. 7C) for detecting a direction, a current supply unit (current supply unit) 30 for supplying a pulse current to the track 5 of the magnetic disk 50, and a control for controlling them. Section (selection means, data reproduction means) 40.

  In the magnetic reproducing apparatus, the magnetic head 21 of the track 5 of the magnetic disk 50 is detected by the detection unit 20A including the magnetic head 21 made of a magnetoresistive effect element such as a GMR element or a TMR element, as in the current magnetic disk reproduction. The magnetization direction in the opposing region is detected. As shown in FIG. 7C, the detection unit 20 </ b> A further includes a power source that supplies current to the magnetic head 21 by connecting to a pair of electrodes (not shown) of the magnetic head 21, and an ammeter. The magnetic head 21 is supported by an arm (not shown) and is movably provided so as to be opposed to each one of all tracks 5 of the magnetic disk 50, that is, the reproduction area 5r. The position of the reproduction area 5 r on the track (magnetic thin wire) 5 is as described in the embodiment of the magnetic recording medium (magnetic disk) 50. Therefore, in the magnetic reproducing apparatus, when the reproducing area 5r is arranged on the radius of a circle in a plan view like the magnetic disk 50 shown in FIG. 1, the magnetic head 21 is arranged in a linear direction along the radius. It only needs to be movable. As described above, the magnetic reproducing apparatus has the same configuration as that of the current magnetic reproducing apparatus except that the magnetic reproducing apparatus includes the current supply unit 30 instead of the magnetic disk rotation driving mechanism. A magnetic recording / reproducing apparatus capable of recording data by further providing writing means such as a recording magnetic head 22 (see FIG. 4 (a)) composed of magnetic poles together with the magnetic head 21 may be used.

[Magnetic reproduction method]
A method for reproducing a magnetic disk by the magnetic reproducing apparatus according to the present invention will be described. In the present embodiment, the selection process and the reproduction process are repeated as necessary in the same manner as the magnetic disk reproduction method by the magneto-optical magnetic reproducing apparatus described above, and the magnetization direction of the magnetic thin wire is detected by the magnetic system.

(Selection process)
In the selection step, the control unit 40 selects one track 5 from the tracks (magnetic thin wires) 5, 5,. In the present embodiment, when the track 5 is selected, the control unit 40 drives the arm to move the magnetic head 21 of the detection unit 20A to a position facing the reproduction area 5r of the track 5. Then, the control unit 40 connects the current supply unit 30 to the electrodes 61 and 62 of the track 5 so as to supply a pulse current to the track 5, and shifts to the reproduction process.

(Regeneration process)
In the reproduction process, the current supply unit 30 supplies a pulse current to the track (magnetic thin line) 5 of the magnetic disk 50 selected in the selection process in the direction of the thin line, and moves the data area intermittently with the domain wall (current). Supply process), the detection unit 20A detects the magnetization direction in the reproduction region 5r of the track 5 (magnetic detection process), and the control unit 40 sets the magnetization direction detected when the current in the pulse current is stopped to “0” or “1”. The data is converted and reproduced (data reproduction process). Therefore, the current supply process is performed in the same manner as the magnetic reproduction method using the magneto-optical method, while the irradiation process is not performed, and the magnetic detection process is performed instead of the photodetection process. Since the current supply process is as described above, the description thereof is omitted. Hereinafter, the magnetic detection process will be described.

(Reproduction process: Magnetic detection processing)
As in the current magnetic disk, as shown in FIG. 7C, for example, a GMR element as the magnetic head 21 of the detection unit 20A leaks from the data region (magnetic domain) of the magnetic thin wire 5 in the opposing reproduction region 5r. As a result, the resistance of the GMR element is changed. The current value is measured by an ammeter provided in the detection unit 20A, and the direction of the leakage magnetic field is determined based on, for example, a preset threshold value to detect the magnetization direction of the magnetic wire 5 in the reproduction region 5r. Therefore, the reproducing area 5r is set to a length in the direction of a thin line where a leakage magnetic field detectable by the magnetic head 21 (GMR element) is obtained. In the magnetic reproducing method according to the present invention, unlike the current magnetic disk, the magnetic disk 50 does not rotate at a high speed, so that the magnetic head 21 does not lift from the magnetic disk 50 and is in contact with the surface. A magnetic field can be detected.

(Reproduction process: Data reproduction process)
Similar to the data reproduction process in the magnetic reproduction method using the magneto-optical method, the control unit 40 recognizes the reproduction data as “0” or “1” from the detected magnetization direction when the current in the pulse current stops, and converts it into a signal. To do.

  As described above, also in the reproduction by the magnetic method, the magnetization direction is detected from the reproduction region 5r as a predetermined region while moving the data region in the track (magnetic thin wire) 5 similarly to the magneto-optical method. When all the data stored in the track 5 is reproduced, the supply of the pulse current is stopped, the reproduction process is completed, and a new track 5 is selected again in the selection process.

  As described above, according to the magnetic reproducing device and the magnetic reproducing method according to the present invention, as in the reproduction by the magneto-optical method, the data area is not misaligned so as to cause a reproduction error in the reproduction area 5r. Since one data area always reaches the whole reproduction area 5r at the time of stop, the data can be accurately reproduced by the magnetic head 21.

(Modification of magnetic reproducing device)
In the present embodiment, one track 5 is selected from the magnetic disk 50 and data is reproduced. However, a magnetic reproducing apparatus using a magnetic system also has, for example, a reproduction area 5r of two different tracks 5 and 5. If the detection unit 20A is configured to include two magnetic heads (magnetoresistance effect elements) 21 and 21 that can be opposed to each other and can measure the current values of the respective magnetic heads 21 in parallel, the two tracks 5 are provided. , 5 can be reproduced in parallel (not shown).

  As described above, in the reproduction of the magnetic recording medium according to the present invention, the reproduction area for detecting the magnetization direction of the magnetic wire at the position corresponding to the high saturation magnetization area formed on the magnetic wire of the magnetic recording medium. The data can be accurately reproduced at high speed.

  The local region partitioned by ion implantation into the magnetic wire and partitioned in the direction of the thin wire having a high saturation magnetization has an effect of locking the same domain wall as the constriction (notch) of the magnetic wire. Therefore, the magnetic recording medium (magnetic disk) is not limited to a magnetic recording medium in which a large number of data is continuously recorded using a magnetic thin wire as a track, and data of “0” and “1” is 2 as a magnetization direction. A high saturation magnetization region can be used for all of the magnetic fine lines that are recorded as described above, that is, two or more magnetic domains are formed and moved by a desired distance in the direction of the fine lines. Hereinafter, the light modulation element to which the magnetic wire is applied will be described.

[Light modulation element, spatial light modulator]
FIG. 9 shows a spatial light modulator to which the light modulation element according to the present invention is applied as a pixel, and FIG. 10 shows a display device using this spatial light modulator. In addition, the plane (upper surface) in this embodiment is a light incident surface of the spatial light modulator. In FIG. 9, in order to show the planar view shape and magnetization direction of the magnetic thin wire, a part of the upper electrode is cut away.

  As shown in FIG. 9, the spatial light modulator 1B selects a pixel array 50B in which the light modulation elements 2B are arranged in a two-dimensional array on the substrate 7B, and one or more pixels from the pixel array 50B. And a current control unit 30B to be driven. In addition, the pixel in this specification refers to a means for presenting information (bright / dark) in the minimum unit of display by the spatial light modulator.

  As shown in FIG. 9, the pixel array 50 </ b> B is illustrated as a configuration including 16 pixels (light modulation elements 2 </ b> B) of 4 rows × 4 columns as an example, and is extended in the row (lateral) direction in plan view. Four striped upper electrodes 62B, and four lower electrodes 61B that are also striped and extend in the column (vertical) direction so as to be orthogonal to the upper electrodes 62B in plan view. One pixel, that is, a light modulation element 2B is provided for each intersection of 62B and the lower electrode 61B. Accordingly, in the pixel array 50B, four light modulation elements 2B arranged in the row direction share one upper electrode 62B, and four light modulation elements 2B arranged in the column direction share one lower electrode. 61B is shared. The upper electrode 62B and the lower electrode 61B are collectively referred to as electrodes 61B and 62B as appropriate.

  Each pixel (light modulation element 2B) includes a magnetic body (hereinafter referred to as a magnetic wire) 5B formed in a thin line shape in the gap between the lower electrode 61B and the upper electrode 62B, and a lower surface near one end of the magnetic wire 5B. The lower electrode 61B is connected to the upper electrode 62B, and the upper electrode 62B is connected to the upper surface near the other end. Therefore, the light modulation element 2B includes the magnetic thin wire 5B and the upper electrode 62B and the lower electrode 61B having different combinations for each pixel connected to both ends thereof. Further, the gap in the pixel array 50B, that is, the space between the upper electrodes 62B and 62B, the space between the lower electrodes 61B and 61B, and the space between the magnetic wires 5B and 5B is filled with the insulating layer 8. The size (pitch, so-called pixel size) of the light modulation element 2B is the light from the optical system 10B that irradiates the pixel array 50B when the spatial light modulator 1B is used in a display device (see FIG. 10) described later, for example. Although it depends on the wavelength of (incident light), it is preferably about 200 nm or more, and preferably 1 mm or less.

  As shown in FIG. 9, the current control unit 30B controls the lower electrode selection unit 31 that selects the lower electrode 61B, the upper electrode selection unit 32 that selects the upper electrode 62B, and these electrode selection units 31 and 32. The pixel selection part 40B and the power supply 33 which supplies an electric current to the electrodes 61B and 62B are provided. As these, known ones can be applied, and appropriate voltages and currents are supplied to the light modulation element 2B.

  The lower electrode selection unit 31 selects one or more of the lower electrodes 61B, and the upper electrode selection unit 32 selects one or more of the upper electrodes 62B, and each supplies a predetermined current from the power source 33. For example, the pixel selection unit 40B selects one or more specific pixels (light modulation element 2B) of the pixel array 50B based on an external signal (not shown), and electrodes 61B and 62B connected to the selected light modulation element 2B. Are selected by the electrode selectors 31 and 32. The power supply 33 supplies a current to the magnetic thin wire 5B in the selected light modulation element 2B in one direction in one direction or the opposite direction. With such a configuration, a specific pixel, that is, the light modulation element 2B is selected, and a current is supplied to the magnetic thin wire 5B of the light modulation element 2B to perform the operation described later.

(Magnetic wire)
A known magneto-optical material can be applied to the magnetic thin wire 5B, and a perpendicular magnetic anisotropic material or an in-plane magnetic anisotropic material may be used in the same manner as the magnetic thin wire 5 of the magnetic recording medium (magnetic disk) 50 according to the present invention. But you can. In the spatial light modulator 1B, the magnetic wire 5B is made of an in-plane magnetic anisotropic material. The width of the magnetic wire 5B is preferably 100 μm or less, and preferably 100 nm or more, although it depends on the wavelength of incident light and the like. The thickness (film thickness) of the magnetic wire 5B is preferably in the range of 10 nm to 2 μm. The length of the magnetic thin wire 5B in the thin wire direction is sufficiently long with respect to the thickness and width, and is set corresponding to the size of the light modulation element 2B, and is preferably in the range of about 200 nm to 500 μm. Further, the distance between adjacent magnetic wires 5B, 5B is preferably 40 nm or more. As shown in FIG. 9, in this embodiment, the magnetic thin wire 5B is inclined 45 ° in the direction parallel to the diagonal line of the pixel array 50B, that is, in a plan view, but is not limited thereto. . Further, the planar view shape of the magnetic thin wire 5B is a straight shape (elongated rectangle), but is not limited to this, and is formed in a curved shape such as an arc as long as it does not hinder the movement of the domain wall DW described later. Also good.

  In the present embodiment, the magnetic thin wire 5B is a region where light enters at the center in the thin wire direction, and this region is the reproduction region 5r (see FIG. 10) like the magnetic thin wire 5 of the magnetic disk 50, and its length. Is preferably about 200 nm or more. The reproduction area 5r is set to a predetermined area divided in the thin line direction excluding the vicinity of both ends of the magnetic thin line 5B. The magnetic fine wire 5B is formed by ion implantation of high Ms regions (high saturation magnetization regions) 5s1 and 5s2 having relatively high saturation magnetization on both sides of the reproduction region 5r in the thin wire direction. Since the saturation magnetization and the length in the fine line direction of the high Ms regions 5s1 and 5s2 are the same as those in the high Ms region 5s in the magnetic fine wire 5 of the magnetic disk 50, description thereof is omitted. The positions of the high Ms regions 5s1 and 5s2 in the magnetic wire 5B are 5 to 40% of the total length of the magnetic wire 5B from the respective ends of the magnetic wire 5B, and the interval between the high Ms regions 5s1 and 5s2 is 30 to 90% of the same length. Preferably, the reproduction area 5r is set between the high Ms areas 5s1 and 5s2. The distances from the ends of the magnetic fine wires 5B of the two high Ms regions 5s1 and 5s2 may not be equal. Furthermore, only one of the high Ms regions 5s1 and 5s2 may be formed on one side of the reproduction region 5r of the magnetic wire 5B.

  The electrodes 61B and 62B are a pair of electrodes connected to both ends of the magnetic wire 5B, similarly to the electrodes 61 and 62 connected to the magnetic wire 5 of the magnetic disk 50, and a current is supplied to the magnetic wire 5B in the direction of the wire. A current is supplied from the control unit 30B (power supply 33). A common metal electrode material can be applied to the electrodes 61B and 62B, and the electrodes 61B and 62B are formed on the substrate 7B by a sputtering method or the like, and formed into a stripe shape by photolithography or the like. The thickness and width are set depending on the material, supplied voltage / current, and the like, but are preferably 10 nm to 5 μm in thickness and 20 nm to 500 μm in width. Each pitch (wiring pitch) of the upper electrode 62B and the lower electrode 61B corresponds to the pixel size.

A known substrate material can be applied to the substrate 7B in the same manner as the substrate 7 of the magnetic disk 50. It can also be applied to known insulating material for the insulating layer 8, and specific examples thereof include a transparent insulating material as SiO ₂ or Al ₂ O ₃ or the like so as to transmit light incident on the magnetic thin wire 5B is.

Next, an example of the method for manufacturing the light modulation element (spatial light modulator pixel array) according to the present invention will be described.
First, the lower electrode 61B is formed. A metal electrode material is formed on the surface of the substrate 7B by sputtering, and formed into a stripe shape by photolithography or the like. Then, the insulating layer 8 is formed and deposited between the lower electrodes 61B and 61B.

  Next, the magnetic wire 5B is formed. A magneto-optic material is formed on the surface of the substrate 7B on which the lower electrode 61B is formed by sputtering, and is formed into one thin line for each pixel by photolithography and ion milling (ion etching). Alternatively, after a resist mask having a negative pattern of the magnetic wire 5B is formed on the surface of the substrate 7B on which the lower electrode 61B is formed, a magneto-optical material is formed thereon, and the ferromagnetic material thereon is applied together with the resist mask. It may be removed (lift off). Then, similarly to the method for manufacturing the magnetic disk 50, the high Ms regions 5s1 and 5s2 are formed in the magnetic wire 5B by ion irradiation. An insulating layer 8 is formed and deposited between the magnetic wires 5B and 5B. The formation (ion irradiation) of the high Ms regions 5s1 and 5s2 on the magnetic wire 5B may be performed before the upper electrode 62B and the insulating layer 8 are formed on the magnetic wire 5B. The ion irradiation method is the same as the method for manufacturing the magnetic disk 50.

  Then, the upper electrode 62B is formed. Similarly to the lower electrode 61B, a metal electrode material is formed on the surface of the substrate 7B on which the magnetic fine wires 5B are formed by sputtering, and is formed into stripes by photolithography or the like. Finally, the insulating layer 8 is formed and deposited between the upper electrodes 62B and 62B and on the surface to form the pixel array 50B.

  Next, the operation of the light modulation element according to the present invention will be described with reference to FIG. In the present embodiment, since the magnetic thin wire 5B of the light modulation element 2B (2B0, 2B1) is made of an in-plane magnetic anisotropic material, the magnetization direction is along the thin wire direction. Two magnetic domains, a magnetic domain D1 and a magnetic domain D0 with leftward magnetization, are arranged side by side in the thin line direction across the domain wall DW. In FIG. 10, the current supply to the magnetic wire 5B is stopped, and the domain wall DW is placed in the high Ms region 5s1 in the left light modulation element 2B0 and in the high Ms region 5s2 in the right light modulation element 2B1. Is locked. Therefore, in the reproduction region 5r of the magnetic thin wire 5B of each of the light modulation elements 2B0 and 2B1, since the magnetic domain D0 is present in the light modulation element 2B0, the leftward magnetization is exhibited, and in the light modulation element 2B1, the magnetic domain D1 is present. Shows magnetization.

  A current is supplied to the magnetic thin wire 5B in the left direction by the electrodes 61B and 62B to the light modulation element 2B0 in this state. Specifically, in the current control unit 30B, the current is supplied from the electrode 62B to the electrode 61B by setting the lower electrode 61B to “−” and the upper electrode 62B to “+”. Then, the domain wall DW moves to the right in the direction opposite to the direction of the current, similarly to the shift movement of the domain wall in the magnetic wire 5 of the magnetic disk 50 (see FIG. 6). In the magnetic thin wire 5B, only two magnetic domains D1 and D0 and one domain wall DW between them are formed. Therefore, as the domain wall DW moves, the left domain D1 expands and the right domain D0 contracts. . When the current is stopped by moving the domain wall DW by the distance of the length between the high Ms regions 5s1 and 5s2 depending on the current density and the supply time, the domain wall DW is locked to the high Ms region 5s2 by the light modulation element 2B1. The magnetic domain D1 on the left side of the domain wall DW is expanded to the reproduction area 5r. This causes the same operation as switching from the magnetic domain D0 to the magnetic domain D1 in the reproducing region 5r of the magnetic wire 5B and reversing the magnetization to the right. On the contrary, for the light modulation element 2B1, when the lower electrode 61B is set to “+” and the upper electrode 62B is set to “−” and current is supplied to the magnetic thin wire 5B in the right direction, the domain wall DW moves to the left, and the light modulation element 2B0, and the magnetization is reversed leftward in the reproduction region 5r.

  As described above, the magnetization direction in the reproduction region 5r of the magnetic wire 5B can be set to a desired direction by changing the direction of the specific pixel (light modulation element 2B) from the electrodes 61B and 62B and supplying the current. . The current is preferably a pulse current as in the data reproduction of the magnetic disk 50, and the domain wall DW is set to a pulse width that moves the distance between the high Ms regions 5s1 and 5s2. Of course, the high Ms regions 5s1 and 5s2 may be moved by supplying current twice or more (two clocks or more). Similarly to the magnetic thin wire 5 of the magnetic disk 50 according to the present invention, the magnetic wire 5B is provided with the high Ms regions 5s1 and 5s2, so that there is no displacement of the domain wall DW, and the magnetic domain in the reproduction region 5r when the current is stopped. Only one of D0 and D1 exists. When light of one polarization component (incident polarization in FIG. 10) enters such a light modulation element 2B, the light is rotated and emitted as light of another uniform polarization component (emitted polarization), so that stable light modulation is performed. Operation is obtained.

  Next, the operation of the spatial light modulator to which the light modulation element according to the present invention is applied as a pixel will be described with reference to FIG. 10 as a display device using the spatial light modulator. As described above, the electrodes 61B and 62B are connected to the current control unit 30B. Also, above the pixel array 50B of the spatial light modulator 1B, there is an optical system 10B that irradiates light toward the pixel array 50B, and one light before the light emitted from the optical system 10B enters the pixel array 50B. Polarizer PFi as the incident polarization of the polarization component light, a polarizer PFo that transmits only polarized light in a specific direction from the light reflected and emitted from the pixel array 50B, and detection that detects the light transmitted through the polarizer PFo The part 20B is arranged. Similarly to the optical system 10 of the magnetic reproducing apparatus 1 shown in FIG. 2, the optical system 10B is a laser irradiation device 11 that is a light source, and a laser beam emitted from the laser irradiation device 11 is irradiated onto a pixel array 50B ( And a lens group 12 for making the collimated light with a spot diameter suitable for all the light modulation elements 2B). In addition, since the pixel array 50B is irradiated with parallel light, the objective lens 15 is not provided. The detection unit 20B is an image display unit such as a screen or an imaging device such as a camera.

  The incident polarized light irradiated from the optical system 10B and transmitted through the polarizer PFi enters the pixel array 50B at a predetermined incident angle as shown in FIG. Incident polarized light passes between the upper electrodes 62B and 62B (transmits through the insulating layer 8) and is reflected by the magnetic wire 5B to become outgoing polarized light, which is again emitted from the pixel array 50B through the upper electrodes 62B and 62B. The polarizer PFo is reached. The polarizer PFo shields the polarized light rotated at a predetermined angle with respect to the incident polarized light, and the output polarized light transmitted through the polarizer PFo is irradiated to the detection unit 20B.

  When the incident polarized light is reflected by the magnetic wire 5B, it is rotated by an angle of −θk or + θk in a direction corresponding to the magnetization direction in the reproduction region 5r of the magnetic wire 5B by the magneto-optic Kerr effect. The polarizer PFo shields light that has been rotated by + θk with respect to incident polarized light. For this reason, the outgoing polarized light from the right light modulation element 2B1 in FIG. 10 reflected by the magnetic thin wire 5B magnetized in the right direction is shielded by the polarizer PFo. On the other hand, the outgoing polarized light from the light modulation element 2B0 on the left side of FIG. 10 passes through the polarizer PFo and is irradiated to the detection unit 20B. Accordingly, the left pixel (light modulation element 2B0) in FIG. 10 is bright (white), and the right pixel (light modulation element 2B1) is dark (black) and displayed on the detection unit 20B. As described above, each of the light modulation elements 2B in the pixel array 50B reverses the magnetization direction to the right / left in the reproduction region 5r of the magnetic wire 5B corresponding to the direction of the current supplied from the electrodes 61B and 62B. Therefore, light / dark (white / black) can be separated for each pixel, and light / dark can be switched by switching the current direction. As an initial state of the spatial light modulator 1B, in order to align all the pixels in the pixel array 50B to, for example, a bright state (white display), an external magnetic field having an appropriate strength and direction is applied to the pixel array 50B. Thus, one magnetic wall DW may be generated and locked to the high Ms region 5s1 for the magnetic thin wires 5B of all the light modulation elements 2B.

  Further, in order to increase the optical rotation angles −θk, + θk (| θk |), that is, to increase the magneto-optical effect (Kerr effect) of the magnetic wire 5B, the incident polarized light depends on the magnetization direction in the incident region 5r of the magnetic wire 5B. Incident light is preferably incident along a direction close to parallel. In the spatial light modulator 1B according to the present embodiment, the magnetization direction of the magnetic thin wire 5B in the incident region 5r is the thin wire direction of the magnetic thin wire 5B, and is the diagonal direction of the pixel array 50B as shown in FIG. However, if the incident direction is too close to the magnetization direction, it becomes difficult for light to enter the incident region 5r of each magnetic thin wire 5B. Therefore, the incident angle of the magnetic thin wire 5B is within about 80 °. It is preferable that the direction is an angle of about 10 ° to 60 ° with respect to the thin line direction. Therefore, in the spatial light modulator 10 according to the present embodiment, since the incident direction of the incident polarized light is inclined so as to be in the range of the incident angle of about 30 ° to 80 °, as shown in FIG. An optical system 10B, polarizers PFi, Pfo, and the like are arranged in accordance with the respective optical paths of polarized light.

In FIG. 10, the light modulation element 2B is a pixel of the reflective spatial light modulator 1B in which light incident from above is reflected by the magnetic wire 5B and emitted again upward. Not limited to this, the magnetic wire 5B may be formed of a highly transmissive magneto-optic material, and may be a light modulation element that transmits light and rotates by the Faraday effect. Such a light modulation element can be arranged on a transparent substrate such as glass, SiO ₂ , Al ₂ O ₃ , MgO, or the like to form a transmissive spatial light modulator (not shown). About such a spatial light modulator, a polarizer PFo and a detection unit 20B are disposed below to form a display device.

(Modification)
A spatial light modulator according to a modification in which another light modulation element according to the present invention is applied as a pixel will be described with reference to FIG. The spatial light modulator 1C according to this modification has the same configuration as that of the spatial light modulator 1B (see FIG. 10) except for the magnetic wire 5C, and the same components are denoted by the same reference numerals and description thereof is omitted. The magnetic wire 5C is made of a perpendicular magnetic anisotropic material, and the shape of the pixel array 50C in plan view is the same as that of the pixel array 50B shown in FIG. 9 except for the magnetization direction of the magnetic wire 5C.

  As shown in FIG. 11, the magnetization direction of the magnetic wire 5C is upward (magnetic domain D1) or downward (magnetic domain D0), and the movement of the domain wall DW due to current supply and the accompanying expansion and contraction of the magnetic domains D1, D0 This is the same as the magnetic wire 5B made of the inner magnetic anisotropic material (see FIG. 10), and the magnetization direction can be reversed in a desired direction, either downward or upward, in the incident region 5r.

  The magnetic fine wire 5C has a low Ms region 5e formed by ion implantation in a region containing the incident region 5r at the center in the thin wire direction (substantially the same region as the incident region 5r in FIG. 11). In other words, in the magnetic wire 5C, high Ms regions 5s1 and 5s2 are formed from both outer sides to the end of the incident region 5r (see the left side light modulation element 2C (2C0) in FIG. 11). By providing the low Ms region 5e in the magnetic thin wire 5C, when the domain wall DW reaches near the inner / outer interface of the low Ms region 5e due to the displacement of the current supply, it spontaneously moves out of the low Ms region 5e when the current stops. Move and then stop. Therefore, when the current is stopped, there is no domain wall DW in the reproduction region 5r, and only one of the magnetic domains D0 and D1 exists. In the manufacture of the pixel array 50C having such magnetic thin wires 5C, it is sufficient to form a mask having a central portion of the magnetic thin wires 5C of each light modulation element 2C (pixel) and perform ion irradiation. The shape can be simplified.

  In the spatial light modulator 1C, as shown in FIG. 11, light (incident polarized light) is incident parallel to the magnetization direction of the magnetic wire 5C, that is, perpendicular to the pixel array 50C (in-plane direction of the pixel array 50C). Thus, the magneto-optical effect can be increased, and it is preferable that the incident angle of incident polarized light is within about 30 °. Although not shown in FIG. 11, in the display device using the spatial light modulator 1C as in the spatial light modulator 1B shown in FIG. 10, the optical system 10B and the polarizer PFi are disposed above the pixel array 50C. Deploy.

  Further, since the spatial light modulator 1C has the magneto-optical effect maximized by making incident polarized light perpendicularly incident on the pixel array 50C, the optical system 10B and the polarizer PFi are disposed immediately above the pixel array 50C. Most preferably, the incident polarized light is incident at an incident angle of 0 °. In the display device having such a configuration, the light reflected from the pixel array 50C and emitted (emitted polarized light) has the same optical path as the incident polarized light, and thus the pixel array 50C is provided between the polarizer PFi and the pixel array 50C. A half mirror inclined by 45 ° is further arranged. Therefore, the polarizer PFo and the detection unit 20B are disposed on the side of the half mirror (not shown).

  As described above, in the light modulation element according to the present invention, a region having a high saturation magnetization is locally formed in the magnetic wire by ion implantation, so that the region is constricted with the magnetic wire (see FIG. 3B). The magnetic domain wall has the effect of locking the same, and the desired magnetization direction can be accurately set in a predetermined region where light is incident, so that the light modulation operation is stabilized. Furthermore, unlike the constriction formed by processing the magnetic fine wire, the light is not diffusely reflected on the surface and the light extraction efficiency is not impaired.

  As described above, the magnetic recording medium, the magnetic reproducing apparatus and the magnetic reproducing method thereof, and the modes for carrying out the light modulation element according to the present invention have been described, but the present invention is not limited to these embodiments. Various modifications can be made within the scope of the claims.

DESCRIPTION OF SYMBOLS 1 Magnetic reproducing apparatus 10 Optical system (irradiation means)
1B, 1C Spatial light modulator 20 detector (light detection means)
20A detector (magnetic detection means)
2B, 2C Light modulation element 30 Current supply unit (current supply means)
40 Control unit (selection means, data reproduction means)
50 Magnetic disk (magnetic recording medium)
50B, 50C Pixel array 5 Magnetic wire (track)
5s High Ms region (High saturation magnetization region)
5e Low Ms area 5r Reproduction area 5w Recording area 5B, 5C Magnetic wire 5s1, 5s2 High Ms area (high saturation magnetization area)

Claims (8)

One or more magnetic thin wires formed by forming a magnetic material on a substrate in a thin line shape are provided, and binary data is continuously input to the magnetic thin wire as one of two different magnetizations in the thin wire direction of the magnetic thin wire. By recording and supplying a pulse current from one end of the magnetic wire to the other end in the direction of the thin wire, in the magnetic wire, the magnetic domain formed by recording one of the binary data and the other of the binary data A magnetic recording medium in which a domain wall generated between magnetic domains formed by recording data moves intermittently in a thin line direction,
The magnetic thin wire includes a high saturation magnetization region in a region partitioned in the direction of the thin wire as a region for reaching the domain wall when the current in the pulse current stops.
The magnetic recording medium according to claim 1, wherein the magnetic thin line is formed in advance by relatively increasing the saturation magnetization of the high saturation magnetization region by implanting ions other than the high saturation magnetization region.   2. The substrate according to claim 1, wherein the substrate has a disk shape, and the magnetic fine wire is formed on the substrate in a concentric shape with a shape lacking a part of an annulus in plan view. Magnetic recording media.   The magnetic recording medium according to claim 1, wherein the magnetic wire is made of a magneto-optical material. A magnetic reproducing apparatus for reproducing binary data recorded on the magnetic recording medium according to claim 1 or 2,
Selecting means for selecting one or more magnetic wires from the magnetic recording medium;
Current supply means for supplying a pulse current in the direction of the thin wire connected to both ends of the magnetic fine wire to the magnetic thin wire selected by the selection means, and intermittently moving the domain wall generated in the magnetic thin wire;
Magnetic detection means for detecting a magnetization direction in a region at a position designated in advance for detecting the magnetization direction in the magnetic thin wire selected by the selection means;
Magnetic reproduction comprising: data reproduction means for reproducing, as data, the magnetization direction detected by the magnetic detection means when the current in the pulse current is stopped in synchronization with the pulse current supplied by the current supply means apparatus. A magnetic reproducing apparatus for reproducing binary data recorded on the magnetic recording medium according to claim 3,
Selecting means for selecting one or more magnetic wires from the magnetic recording medium;
Current supply means for supplying a pulse current in the direction of the thin wire connected to both ends of the magnetic fine wire to the magnetic thin wire selected by the selection means, and intermittently moving the domain wall generated in the magnetic thin wire;
In the magnetic wire selected by the selection means, an irradiation means for causing light to enter a region at a position designated in advance for detecting the magnetization direction;
A light detecting means for detecting the direction of polarization of light incident from the irradiation means and emitted from the magnetic wire;
Data reproducing means for reproducing, as data, the polarization direction of the light detected by the light detection means when the current in the pulse current is stopped in synchronization with the pulse current supplied by the current supply means; Magnetic reproducing device. A magnetic reproducing method for reproducing binary data recorded on the magnetic recording medium according to claim 1 or 2,
A selection step of selecting one or more magnetic wires from the magnetic recording medium;
A reproducing step of reproducing the data recorded on the selected magnetic wire of the magnetic recording medium,
In the reproducing step, a current supply process for supplying a pulse current for intermittently moving a magnetic domain wall generated in the magnetic wire to the magnetic wire in the direction of the wire;
A magnetic detection process for detecting a magnetization direction in a region at a predesignated position for detecting the magnetization direction of the magnetic wire;
In synchronization with the pulse current supplied in the current supply process, a data reproduction process for reproducing the magnetization direction detected in the magnetic detection process when the current in the pulse current is stopped as data is performed. Magnetic replay method. A magnetic reproducing method for reproducing binary data recorded on the magnetic recording medium according to claim 3, comprising:
A selection step of selecting one or more magnetic wires from the magnetic recording medium;
A reproducing step of reproducing the data recorded on the selected magnetic wire of the magnetic recording medium,
In the reproducing step, a current supply process for supplying a pulse current for intermittently moving a magnetic domain wall generated in the magnetic wire to the magnetic wire in the direction of the wire;
An irradiation process in which light is incident on a region at a predesignated position for detecting the magnetization direction of the magnetic wire;
A light detection process for detecting the direction of polarization of light incident on the irradiation process and emitted from the magnetic wire;
In synchronization with the pulse current supplied in the current supply process, a data reproduction process for reproducing the polarization direction of the light detected in the light detection process as data when the current in the pulse current is stopped is performed. A magnetic reproducing method. A magnetic thin line formed by forming a magneto-optic material in a thin line shape on a substrate, and a pair of electrodes connected to both ends of the magnetic thin line, and changing the direction of polarization of light incident on the magnetic thin line is emitted. In the light modulation element, the magnetic thin wire has two or more magnetic domains formed continuously in the thin wire direction, and current is supplied in the thin wire direction through the pair of electrodes, so that two adjacent magnetic domains The domain wall generated between them is moved in the direction of the thin line, and one of the two magnetic domains is selectively made to reach the incident region which is a region divided in the direction of the thin line where the light is incident,
The magnetic thin wire includes a high saturation magnetization region partitioned in a thin wire direction outside the incident region as a region for reaching the domain wall when the current is stopped,
The light modulation element according to claim 1, wherein the magnetic thin line is formed in advance by relatively increasing the saturation magnetization of the high saturation magnetization region by implanting ions other than the high saturation magnetization region.

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