JPH04281203A - Composite type thin film magnetic head and magnetic recorder - Google Patents

Abstract

PURPOSE:To increase density in the record of a composite thin film magnetic head by equalizing an interval between a pair of magnetic domain control layers in a magneto-resistance effect type magnetic head for reproducing having a pair of magnetic domain control layers provided on both ends of a magneto- resistance effect type film and the track width of an electromagnetic induction magnetic head for recording or narrowing the interval narrower than the width. CONSTITUTION:An interval L2 between the pair of the magnetic domain control layers 41, 42 constituting the magneto-resistance effect type magnetic head for reproducing is wider than an interval L3 between a pair of electrode conductors 51, 52. Also, a track width L1 to be the width of an upper magnetic core 14 in a floating plane 81 constituting the electromagnetic induction magnetic head for recording is winder than the space between the pair of magnetic domain control layers 41, 42 of the head for reproducing. In such a manner, voltage change does not occur substantially to the noise component except of a prescribed track and the voltage change are enlarged to the signal component of the prescribed track.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a composite thin-film magnetic head used in magnetic recording devices such as magnetic disk drives, magnetic tape drives, and VTRs, and in particular, a composite thin-film magnetic head and magnetic recording device suitable for high-density recording. Regarding.

0002

[Prior Art] Conventionally, a composite thin-film magnetic head that combines an electromagnetic induction magnetic head for recording and a magnetoresistive magnetic head for reproduction, and a magnetic recording device that performs recording and reproducing operations with the composite thin-film magnetic head. is suitable for high-density recording. However, in magnetoresistive magnetic heads for reproduction, noise called Barkhausen noise occurs due to irregular movement of domain walls, and signals from a recording medium are often reproduced erroneously. US Pat. No. 4,103,315 discloses that by exchange coupling an antiferromagnetic film and a magnetoresistive film, the magnetoresistive effect is made into a single domain, thereby preventing Barkhausen noise. In the present invention, a layer provided for making a magnetoresistive film into a single magnetic domain is defined as a magnetic domain control layer. In a structure in which a magnetic domain control layer made of an antiferromagnetic film or the like is laminated over the entire surface of the magnetoresistive film, the magnetic field required to rotate the magnetization of the magnetoresistive film becomes large, and the sensitivity to the signal magnetic field decreases, resulting in a high density Recording is not possible. The problem with this conventional technology is to pattern the magnetic domain control layer and
This problem was solved by arranging the magnetoresistive film only in the edge region. This method is described in US Pat. No. 7,661,57. In that invention, a magnetic domain control layer is arranged only in the end region of the magnetoresistive film, and this region is maintained in a single magnetic domain state. This single magnetic domain state in the end region also induces a single magnetic domain state in the magnetically sensitive portion at the center of the magnetoresistive film. Therefore, the magnetically sensitive part, which is the track part that reproduces information on the recording medium, is in a single magnetic domain state, and there is no Barkhausen noise, and the magnetic field required to rotate the magnetization is not large, making it suitable for high-density recording. That is clear. Further, in US Patent No. 071491, a soft magnetic film layer for ensuring the linearity of the reproduced waveform contacts only the end region of the magnetoresistive film, and a magnetic domain control layer is provided on the entire surface of the soft magnetic film layer. A magnetic read transducer with an antiferromagnetic film in contact is disclosed. Even in this known example, the magnetoresistive film is in a single magnetic domain state and has high sensitivity, so it is suitable for high-density recording.

0003

[Problems to be Solved by the Invention] There are unresolved problems in the prior art. In other words, the conventional technology only states that the position of the magnetic domain control layer disposed at the end of the magnetoresistive film is located in the end region from the magnetically sensitive part, and the position of the magnetic domain control layer disposed at the end of the magnetoresistive film is in the end region, compared to the recording electromagnetic induction magnetic head. It is not clear where the magnetic domain control layer of the magnetoresistive head should be placed. A large magnetic field is required to rotate the magnetization of the magnetoresistive film in a portion of the magnetoresistive magnetic head for reproduction that is in contact with the magnetic domain control layer. That is, the portion of the magnetoresistive film in contact with the magnetic domain control layer has low magnetic permeability. On the other hand, the portion of the magnetoresistive film not in contact with the magnetic domain control layer has high magnetic permeability. The difference in magnetic permeability between the part of the magnetoresistive film in contact with the magnetic domain control layer and the part of the magnetoresistive film not in contact with the domain control layer has an important effect on realizing high-density recording in a magnetic recording device. Since the portion of the magnetoresistive film that is not in contact with the magnetic domain control layer has a high magnetic permeability, magnetization rotation occurs in response to the magnetic field generated from the recording medium, resulting in a change in magnetoresistance. If a change in magnetoresistance occurs due to a magnetic field from an insufficiently recorded area outside a predetermined track on a recording medium or a track area adjacent to a predetermined track, noise occurs, and high-density recording cannot be achieved.

0004

[Means for Solving the Problems] The main object of the present invention is to provide a pair of magnetic domain control layers for a reproduction magnetoresistive head having a pair of magnetic domain control layers provided at both ends of a magnetoresistive film. An object of the present invention is to provide a composite thin-film magnetic head and a magnetic recording device that realize high-density recording by making the interval equal to or smaller than the track width of an electromagnetic induction magnetic head for recording.

Another object of the present invention is to provide a reproducing magnetoresistive magnetic head having a pair of magnetic domain control layers provided at both ends of a magnetoresistive film, such that the distance between the pair of magnetic domain control layers is equal to the distance between the magnetic domain control layers for recording. By making the track width equal to or smaller than the track width of the inductive magnetic head, and equal to or larger than the spacing between a pair of electrode conductors for flowing a current for signal detection of the magnetoresistive magnetic head for reproduction. An object of the present invention is to provide a composite thin-film magnetic head and a magnetic recording device that perform high-density recording and high-sensitivity recording and reproduction.

[0006]

[Function] The portion of the magnetoresistive film in contact with the pair of magnetic domain control layers provided at both ends of the magnetoresistive film is made of an antiferromagnetic material that constitutes at least a portion of the magnetic domain control layer, or a ferromagnetic material having permanent magnetic properties. Since it is magnetically coupled to a magnetic material, its magnetic permeability is low. Therefore, by arranging the regions of the magnetoresistive film at both ends that are in contact with the magnetic domain control layer inside the track width of the recording electromagnetic induction magnetic head, it is possible to avoid the area outside the predetermined track recorded by the electromagnetic induction magnetic head. Achieves high-density recording and playback without detecting noise components. The magnetoresistive film between the pair of magnetic domain control layers has high magnetic permeability, so it reproduces signals with high sensitivity, and the distance between the pair of magnetic domain control layers is set to be equal to or smaller than the track width of the recording electromagnetic induction magnetic head. In addition, by making the pair of electrode conductors equal to or larger than the pair of electrode conductors for flowing the signal detection current of the magnetoresistive magnetic head for reproduction, the signal-to-noise ratio can be increased, and high-density recording and reproduction can be achieved. Realize.

[0007]

[Embodiment] An embodiment of the present invention will be explained with reference to the drawings. Figure 1
This is one embodiment of the composite thin film magnetic head of the present invention. The magnetoresistive magnetic head for reproduction includes a lower shield film 11 made of NiFe alloy, a lower gap film 21 made of alumina, a magnetoresistive element 31 equipped with means for applying a bias magnetic field to the magnetoresistive film, and a magnetoresistive element 31. 3
A pair of magnetic domain control layers 41 and 42 for making the magnetoresistive film of No. 1 into a single magnetic domain, a pair of electrode conductors 51 and 52 for passing a current for signal detection, an upper gap film 22 made of alumina, and an upper gap film 22 made of NiFe alloy. The upper shield film 12 has an interval L2 between the pair of magnetic domain control layers 41 and 42.
is larger than the distance L3 between the pair of electrode conductors 51 and 52. The recording electromagnetic induction magnetic head includes a lower magnetic core 13 made of NiFe alloy, a gap film 61 made of alumina, a coil 55 made of copper, an upper magnetic core 14 made of NiFe alloy, a lower magnetic core 13 and a coil 5 made of NiFe alloy.
5 and an insulating layer 71 that insulates the upper magnetic core 14, and the track width L1, which is the width of the upper magnetic core 14 on the air bearing surface 81, is the width of the magnetic domain control layer 41 of the pair of magnetoresistive magnetic heads for reproduction. It is larger than the interval L2 of 42. FIG. 1 shows only the main part of the magnetic head near the air bearing surface 81, and the rear magnetic core part, lead wire part, terminal part, protective film, etc. of the recording electromagnetic induction magnetic head are omitted.

In the composite thin film magnetic head of the present invention, information is recorded on the recording medium with a width L1+ΔL compared to the track width L1 of the recording electromagnetic induction magnetic head that records information on the recording medium. ΔL is a positive value because the magnetic field distribution of the recording electromagnetic induction magnetic head is slightly spread in the track width direction. ΔL varies depending on the shape of the recording electromagnetic induction magnetic head, the distance between the magnetic head and the recording medium, the magnetic properties and film thickness of the recording medium, and varies from 0.1 μm to 0.
．． A thickness of about 7 μm is common in high-density magnetic recording. Therefore, the interval between tracks on the recording medium is set to be larger than ΔL so as not to affect adjacent tracks. When reproducing information recorded on multiple tracks using a magnetoresistive head for reproduction, a magnetic field generated from the magnetization reversal region of an adjacent track is applied to the magnetoresistive film of the magnetoresistive head for reproduction. At this time, if the magnetization of the magnetoresistive film rotates significantly, a voltage is generated due to the magnetoresistive effect, resulting in noise. The structure of the magnetoresistive film in the adjacent track area of the magnetoresistive magnetic head for reproduction has a low magnetic permeability and a small rotation angle of magnetization, resulting in low noise. This effect will be explained using FIGS. 2 and 3.

FIG. 2 is a detailed enlargement of only the magnetoresistive element 31, magnetic domain control layer 41, and electrode conductor 51 of the magnetoresistive magnetic head for reproduction shown in FIG. 1, and shows the lower magnetic shield film, lower gap, etc. The film, upper gap film, and upper shield film are omitted.

Magnetoresistive film 31 made of NiFe alloy
1, a shunt conductor 312 for applying a bias magnetic field to the magnetoresistive film 311, and a soft film 313 provided to compensate for the shortage of the bias magnetic field generated from the shunt conductor 312. There is. The shunt conductor 312 is made of Ta, Nb, or T.
An alloy containing a or Nb as a main component is used. For the soft film 313, a CoZrMo amorphous film, NiFeRh, or NiFeZr film ratio, which has a large electrical resistivity, an extremely small magnetoresistive effect, and a relatively large magnetic permeability, is used. Electrode conductor 5
Reference numeral 1 is composed of Au, W, Mo, etc. having low electrical resistivity, or a laminate containing Nb or Ta as an adhesion layer to these metals.

The magnetic domain control layer 41 is an antiferromagnetic material made of FeMn. The part of the magnetoresistive film 3111 that is in contact with the magnetic domain control layer 41 is exchange-coupled with the antiferromagnetic material at the interface, so the magnetic field required for magnetization is large as shown in magnetization curve 1 in FIG. 3, and the magnetic permeability increases. is small. Therefore, sensitivity to magnetic fields from areas other than predetermined tracks of the recording medium is low, and noise is low. On the other hand, the portion of the magnetoresistive film 3112 that is not in contact with the magnetic domain control layer 41 is not exchange-coupled with the antiferromagnetic material, so the magnetic field required for magnetization is small as shown in magnetization curve 2 in FIG. 3, and the magnetic permeability is is large. Therefore, the sensitivity of a given track of the recording medium to the magnetic field is high, and the signal voltage is high. By making the distance L2 between the pair of magnetic domain control layers equal to or smaller than the track width L1 of the recording electromagnetic induction magnetic head, the recording medium has low sensitivity to magnetic fields from other than predetermined tracks. The track width of the reproducing magnetic head is slightly larger than the width L3 of the pair of electrode conductors, but not larger than the distance L2 between the pair of magnetic domain control layers. Therefore, the sensitivity of a given track of the recording medium to the magnetic field is high.

The magnetic recording device of the present invention will be explained with reference to FIG. The recording medium 672 is formed on a disk made of aluminum alloy or glass, and the disk on which the recording medium 672 is formed is rotated by a spindle motor 676 at 1800 to 720 mm.
Rotates at 0 rpm. The composite thin film magnetic head 671 is attached to a gimbal spring 673, and a magnetic head positioning mechanism 674 rotates the gimbal spring in the direction of the arrow in FIG. 4 to position the magnetic head on a predetermined track on the recording medium 672. Recording signals to the magnetic head and reproduction signals from the magnetic head are processed by a signal processing circuit 675. The recording medium 672 has a coercive force of 150, which is suitable for high-density recording.
CoCrTa alloy thin film or CoCrP of 0 Oe or more
It is preferable to use a t-alloy thin film. It is desirable to use a diameter of 5.25 inches or less for the disk on which the recording medium 672 is formed, from the viewpoint of reducing the volume of the entire device. In particular, a disk having a diameter of 2 inches or less is preferable because it places less load on the spindle motor. The magnetic recording device of the present invention is characterized in that it has a particularly high track density, and the track density can be 3,000 tracks or more per inch. By reducing the distance between the lower shield film 11 and the upper shield film 12, the linear recording density can be increased, and 80 kilobits per inch or more can be achieved. Therefore, an areal recording density of 240 megabits per square inch or more can be achieved.

[0013]

According to the present invention, by making the interval between a pair of magnetic domain control layers equal to or smaller than the track width of an electromagnetic induction magnetic head for recording, noise components other than those on a predetermined track can be effectively suppressed. By making the distance between the pair of magnetic domain control layers equal to or larger than the distance between the pair of electrode conductors of the magnetoresistive magnetic head for reproduction without voltage change,
A large voltage change can be obtained for the signal component of a given track.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the vicinity of the tip of a composite thin-film magnetic head according to an embodiment of the present invention.

FIG. 2 is a perspective view of the tip of a reproducing magnetoresistive magnetic head that constitutes a part of the composite thin-film magnetic head.

FIG. 3 is a magnetization curve diagram of a magnetoresistive film in contact with an antiferromagnetic domain control layer and a magnetoresistive film not in contact with an antiferromagnetic domain control layer.

FIG. 4 is a perspective view of the magnetic recording device of the present invention.

[Explanation of symbols]

4... Magnetic domain control film, 11... Lower shield film, 12... Upper shield film, 13... Lower magnetic core, 14... Upper magnetic core,
21... Lower gap film, 22... Upper gap film, 31...
Magnetoresistive element, 51... Electrode conductor, 55... Coil, 6
1... Gap film, 71... Insulating layer, 81... Air bearing surface, 311
... Magnetoresistive film, 312... Shunt conductor, 313... Soft film.

Claims (3)

[Claims] 1. A lower magnetic shield film, a lower gap film made of an insulator, a magnetoresistive film, means for applying a bias magnetic field to the magnetoresistive film, and a magnetoresistive film at both ends of the magnetoresistive film. A reproducing magnetic field consisting of a pair of magnetic domain control layers provided to make the magnetic field into a single magnetic domain, an upper gap film made of an insulator and a pair of electrode conductors for passing current for signal detection, and an upper magnetic shield film. A composite device comprising a recording electromagnetic induction magnetic head composed of a resistive effect magnetic head, a lower magnetic core, a gap film, a coil, an upper magnetic core, a lower magnetic core, and an insulating layer that insulates the upper magnetic core and the coil. 2. A composite thin film magnetic head, characterized in that the distance between the pair of magnetic domain control layers is equal to or smaller than the track width of the recording electromagnetic induction magnetic head. 2. The composite thin film magnetic head according to claim 1, wherein the distance between the pair of magnetic domain control layers is equal to or larger than the distance between the pair of electrode conductors. 3. A magnetic recording medium, a device for driving the magnetic recording medium, a magnetic head, and a circuit for sending electrical signals to be recorded on the magnetic head and processing reproduction signals from the magnetic head. A magnetic recording device using the composite thin film magnetic head.