CN101441195A - Magnetoelasticity performance simultaneous on-line detecting method of iron magnetic thin film - Google Patents

Abstract

An online detection method for magnetoelasticity performance of thin-ferromagnetic-film, which belongs to the field of engineering materials, structure deformation, and mechanical test. The device implementing the method of the invention comprises a thin-ferromagnetic-film non-uniform stress measuring light path and a film hysteresis loop measuring light path, wherein, the film non-uniform stress measuring light path comprises a laser, a beam expander, a grating, a lens, a filter screen, and a CCD camera; and the film hysteresis loop measuring light path comprises a laser, a beam expander, a polarizer, an analyzer, and a photodetector. The method of the invention comprises the steps of measuring non-uniform curvature of the thin-ferromagnetic-film surface by shearing interferometer to obtain the non-uniform stress in film, and measuring the hysteresis loop of the film by using magnetooptic Kerr effect of the thin-ferromagnetic-film surface. The method can simultaneously online measure the non-uniform stress and the hysteresis loop of thin-ferromagnetic-film, so as to provide experimental basis for the research on magnetoelasticity coupling behavior of the thin-ferromagnetic-film.

Description

A kind of magnetoelastic properties of ferromagnetic thin film is online test method simultaneously

Technical field

The present invention relates to a kind of magnetoelastic properties while online test method of ferromagnetic thin film, belong to construction material, structural deformation and Experiments of Machanics technical field.

Background technology

The ferromagnetic thin film material is a class functional material important in microelectronics and the infotech, physical characteristics with multiple uniqueness, as magnetic anisotropy, magnetostrictive effect, magneto-optic effect, magnetoresistance effect etc., aspect a lot of, obtained using widely, along with the development of human society hi-tech, require increasing novel magnetic membraneous material of development and device.Ferromagnetic thin film is also because its excellent power magnetic coupling characteristic, and (MEMS) is widely used in MEMS (micro electro mechanical system), for example, and magnetic microdrive, various microsensor, based on the miniature magnet valve door sensor of magnetoresistance effect etc.

In recent years, existing many Chinese scholars are being studied aspect theory, numerical simulation and the experiment measuring film substrate magnetoelasticity system.Sander has summarized the relation of stress and magnetic anisotropy in the ferromagnetic thin film in detail, discussed based on the magnetoelasticity of crystal structure and described, and measured magnetoelasticity coupling coefficient (Sander D. by the Kerr magneto-optic effect, 1999.The correlationbetween mechanical stress and magnetic anisotropy in ultrathin films.Rep.Prog.Phys., 62:809-858.); People such as Shick (Shick A.B., Novikov D.L.and Freeman A.J.1997.Relativisticspin-polarized theory of magnetoelastic coupling and magnetic anisotropy strain dependence:Application to Co/Cu (001) .Phys.Rev.B56:R14 259-R14262.) have calculated the magnetoelasticity coupling coefficient of Co monofilm based on magnetic anisotropy energy density; Lacheisserie (du Tr ' emolet de Lacheisserie E., 1995.Definitionand measurement of the surface magnetoelastic coupling coefficients in thin films and multilayers.Phys.Rev.B, 51:15925-15932.) influence of surface effect to the magnetoelasticity coupling has been discussed, and studied the contribution of surface to the magnetoelasticity coupling coefficient.Mostly above-mentioned work is to consider magnetoelasticity coupling behavior from the angle of physics, shortage power-magnetic-coupled systematization statement, and the strictness that especially lacks mechanics is derived.

Aspect experiment measuring, current measurement to ferromagnetic thin film magnetoelasticity stress has dual mode: a kind of strain (Vreeland that is based on the direct MEASUREMENTS OF THIN of X-ray diffraction method, T., Dommann, A., Tsai, C.-J.and Nicolet, M.-A., 1988.X-rayDiffraction Determination of Stresses in Thin Films.Mater.Res.Soc.Symp.Proc.30:3-12.), obtain membrane stress by strain according to elastic constitutive relation, employing X ray methods such as Thomas etc. and Dho have been studied the magnetic domain that mismatch stress changes in the film in the film and have been distributed and state (Thomas O., Shen Q., Schieffer P.et al, 2003.Interplay betweenAnisotropic Strain Relaxation and Uniaxial Interface Magnetic Anisotropy in Epitaxial Fe Films on (001) GaAs, Phys.Rev.Lett., 90:17205-17209.); Another kind is a curvature of measuring substrate, set up the relation of curvature and membrane stress by theory of elastic mechanics, this method in the magnetoelasticity coupling measurement, be widely used (Sander D, Enders A.and Kirschner be coupling and epitaxial misfit stress in ultrathinFe (100)-films on W (100) .J.Magn.Magn.Mater.198-199:519-521. J.1999.Magnetoelastic).The X-ray diffraction technology has non-destructive, and does not require special test specimen configuration, and can measure all components of stress in the coating.The restriction of x-ray method maximum is that requirement institute mark degree is relevant with the scale of reference sample with curvature, owing to need mobile example, this method is difficult to use in on-line measurement; This method also is strict point-to-point measurement (point-wise) in addition, can not realize the measurement whole audience, macroscopic view.For the curvature measurement method, need set up membrane stress and curvature relationship (Stoney by the Stoney formula, G.G.The Tension ofMetallic Films Deposited by Electrolysis.Proceedings ofthe Royal Society, A82 (1909): 172-175)

${\mathrm{\σ}}^{\left(f\right)}=\frac{E_s{h}_s^2\mathrm{\κ}}{{6h}_f(1-v_s)}---\left(1\right)$

(1) σ in the formula ^(f)Be membrane stress, E _s, v _sBe respectively the elastic modulus and the Poisson ratio of matrix, h _f, h _sBe respectively film thickness and matrix thickness, κ is the film matrix structure curvature that measures by experiment.

It is based on following basic assumption: film and matrix thickness are even; Film and matrix all are small deformations; Film and matrix all are uniform line resilient materials; Twin shaft states such as stress and curvature distribution are even and be.Biaxial stress state such as this and stress and curvature distribution hypothesis uniformly all are unappeasable in the middle of actual conditions, therefore, utilize the Stoney formula to be distributed by the homogeneous state of stress that curvature obtain film.

Stress state has influenced the magnetic properties of film in the ferromagnetic thin film, and people recognize that gradually the physical meaning of magnetoelasticity coupling and magnetic anisotropy inherent mechanism is far-reaching.The magnetoelasticity of profound understanding ferromagnetic thin film will effectively be improved physical property, serviceable life and the reliability of ferromagnetic thin film, and set up the magnetoelasticity theoretical system of a cover economic, practical, accurate magnetoelasticity coupling performance testing method and technology and ferromagnetic thin film, for preparation, use and the optimal design of ferromagnetic thin film provides foundation.Therefore, stress state from experimental technique and two aspect research of theoretical analysis ferromagnetic thin film and magnetoelasticity just become the important topic in the current ferroelectric thin film research.

Summary of the invention

The invention provides a kind of magnetoelastic properties while online test method of ferromagnetic thin film, this method can overcome above-mentioned the deficiencies in the prior art, the unequal stress and the magnetic hysteresis loop of the ferromagnetic thin film of on-line measurement simultaneously.

Technical scheme of the present invention is as follows:

A kind of magnetoelastic properties of ferromagnetic thin film is online test method simultaneously, it is characterized in that: the non-homogeneous curvature of utilizing shear interference MEASUREMENTS OF THIN surface, by the calculated stress that concerns between curvature and the thin film non-uniform stress, utilize magneto-optical kerr (Kerr) effect on ferromagnetic thin film surface, measure the magnetization of determining film from film surface beam reflected light intensity.

The magnetoelastic properties of ferromagnetic thin film provided by the invention is online test method simultaneously, ferromagnetic thin film unequal stress light path is measured in this method utilization and two light paths of MEASUREMENTS OF THIN magnetic hysteresis loop light path are carried out online detection, and described thin film non-uniform stress is measured light path and comprised the first laser instrument 1a, the first beam expanding lens 2a, the first grating 4a, the second grating 4b, lens 5, filter screen 6 and CCD camera 7; Described MEASUREMENTS OF THIN magnetic hysteresis loop light path comprises the second laser instrument 1b, the second beam expanding lens 2b, polarizer 8, analyzer 9 and photoelectric detector 10, and its detection method comprises the steps:

A. utilize externally-applied magnetic field to make sample 3 magnetization, and record externally-applied magnetic field intensity H;

B. open the first laser instrument 1a, make light beam that first laser instrument sends by the first beam expanding lens 2a, and regulate the first beam expanding lens 2a, make the laser beam expanding that sends from first laser instrument and keep homogeneity;

C. the light beam irradiates after being restrainted by first beam expanding lens 2a expansion is passed through the first grating 4a, the second grating 4b, lens 5, filter screen 6 and CCD camera 7 to sample 3 surfaces successively from the specimen surface beam reflected;

D. the major axes orientation of the first grating 4a and the second grating 4b is arranged to vertical direction, adjusts the distance between lens 5, filter screen 6 and the CCD camera 7, obtain interference image clearly;

E. extract the interference fringe center line, calculate the fringe order variable gradient

With

, n ^(y)Be interference fringe progression, pass through following formula:

${\mathrm{\κ}}_{\mathrm{yy}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(y\right)}}{\∂y}\right),$ ${\mathrm{\κ}}_{\mathrm{xy}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(y\right)}}{\∂y}\right)$

Calculate specimen surface y directional curvature κ _YyWith spin curvature κ _Xy, p is a grating constant in the following formula, Δ is two grating spaces;

F. with the first grating 4a and the second grating 4b in the grating face around the axis on vertical raster plane to the equidirectional half-twist, obtain interference fringe, extract the interference fringe center line, the fringe order number scale is made n ^(x), calculate the fringe order variable gradient

By following formula:

${\mathrm{\κ}}_{\mathrm{xx}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(x\right)}}{\∂x}\right)$

Calculate specimen surface x directional curvature κ _Xx

G. pass through the coordinate conversion formula with the curvature κ under the rectangular coordinate _Xx, κ _Yy, κ _XyConvert the curvature κ under the cylindrical coordinates to _Rr, κ _{θ θ}, pass through following formula:

$\left\{\begin{array}{c}{\mathrm{\σ}}_{\mathrm{rr}}^{\left(f\right)}+{\mathrm{\σ}}_{\mathrm{\θ\θ}}^{\left(f\right)}=\frac{E_s{h}_s^2}{6(1-v_s)h_f}[{\mathrm{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}}+\frac{1-v_s}{1+v_s}({\mathrm{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}}-\stackrel{\‾}{{\mathrm{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}}})]\\ {\mathrm{\σ}}_{\mathrm{rr}}^{\left(f\right)}-{\mathrm{\σ}}_{\mathrm{\θ\θ}}^{\left(f\right)}=-\frac{2E_f{h}_s}{3(1+v_f)}({\mathrm{\κ}}_{\mathrm{rr}}-{\mathrm{\κ}}_{\mathrm{\θ\θ}})\\ \mathrm{\τ}=\frac{E_s{h}_s^2}{6(1-v_s^2)}\frac{d}{\mathrm{dr}}({\text{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}})\end{array}\right.$

Calculate

Obtain the unequal stress of sample, E in the following formula with τ _fBe the thin flexible film modulus, v _fBe the film Poisson ratio, E _sBe matrix elastic modulus, v _sBe the matrix Poisson ratio, h _fBe film thickness, h _sBe matrix thickness,

Be the radial stress in the film, Be the circumferential stress in the film, τ is the shearing stress between film and the basal body interface, d (κ _Rr+ κ _{θ θ})/dr represents the radial derivative of principal curvatures sum;

H. open the second laser instrument 1b, the light beam that second laser instrument is sent passes through the second beam expanding lens 2b; And regulate the second beam expanding lens 2b and make the laser beam expanding that sends from second laser instrument and keep homogeneity;

I. after the light beam behind the second beam expanding lens 2b expansion bundle is by polarizer 8, become linearly polarized light, this linearly polarized light shines sample 3 surfaces, the light beam that reflects from specimen surface passes through photoelectric detector 10 again through analyzer 9, measures received beam intensity I by photoelectric detector;

J. utilize the sample of the known magnetization character of standard to replace sample 3, repeating step i records reflective light intensity I ' because the magnetization character of sample is known, by the magnetic induction density B of externally-applied magnetic field intensity H calculation sample ', the magnetic induction density of sample 3 can calculate by following formula

$B=\frac{I}{I\′}B\′$

Obtain the magnetic induction density B of sample 3;

K. change externally-applied magnetic field intensity H, repeating step i measures the reflective light intensity I of sample 3 under different externally-applied magnetic field intensity H, calculates the magnetic induction density B of sample under different externally-applied magnetic field intensity, draws the magnetic hysteresis loop of sample.

The present invention compared with prior art, have the following advantages and the high-lighting effect: this method can realize the measurement of the whole audience of ferromagnetic thin film curvature, online, real-time, noncontact, non-intervention, simultaneously can avoid vibrating influence, can obtain thin film non-uniform stress by curvature to curvature measurement; The magnetic hysteresis loop of on-line measurement ferromagnetic thin film simultaneously, thus experiment basis provided for the research of the magnetoelasticity coupling behavior of ferromagnetic thin film.

Description of drawings

Fig. 1 is the schematic diagram of the magnetoelastic properties while online test method of ferromagnetic thin film of the present invention.

Among the figure: 1a-first laser instrument; 1b-second laser instrument; 2a-first beam expanding lens; 2b-second beam expanding lens; The 3-sample; 4a-first grating; 4b-second grating; The 5-lens; The 6-filter screen; The 7-CCD camera; The 8-polarizer; The 9-analyzer; The 10-photoelectric detector.

Embodiment

Further specify the specific embodiment of the present invention below in conjunction with accompanying drawing, but should not limit protection scope of the present invention with this.

Fig. 1 is the schematic diagram of the magnetoelastic properties while online test method of ferromagnetic thin film of the present invention, comprise the first laser instrument 1a, the second laser instrument 1b, the first beam expanding lens 2a, the second beam expanding lens 2b, sample 3, the first grating 4a among the figure, the second grating 4b, lens 5, filter screen 6, CCD camera 7, polarizer 8, analyzer 9, photoelectric detector 10.

The described first laser instrument 1a, the first beam expanding lens 2a, the first grating 4a, the second grating 4b, lens 5, filter screen 6, CCD camera 7 constitute thin film non-uniform stress and measure light path, the laser that the described first laser instrument 1a sends arrives on the surface of sample 3 after through the first beam expanding lens 2a, obtains interference pattern through the described first grating 4a, the second grating 4b, lens 5, filter screen 6 and CCD camera 7 successively through the specimen surface beam reflected; The described first laser instrument 1a can provide monochromaticity good and uniform light beam; The light beam that reflects from sample 3 incides the first grating 4a, light beam behind the first grating 4a diffraction incides the second grating 4b, the first grating 4a and the second grating 4b carry out shear interference to light beam, the described first grating 4a is the Ronchi grating with identical grating constant with the second grating 4b, and the distance between two gratings is a Δ; Interference image is analyzed, extracted stripe centerline, calculate thin film non-uniform stress.

The described second laser instrument 1b, the second beam expanding lens 2b, polarizer 8, analyzer 9, photoelectric detector 10 constitute ferromagnetic thin film hysteresis measurement light path, the light beam that the second laser instrument 1b sends by the second beam expanding lens 2b again by becoming linearly polarized light behind the polarizer 8, this linearly polarized light shines sample 3 surfaces, the light beam that reflects from specimen surface passes through photoelectric detector 10 again through analyzer 9, and photoelectric detector 10 is measured the beam intensity that receives.

Principle of work of the present invention is as follows;

Relation between specimen surface curvature and the interference fringe progression is as (2), (3) two formulas:

${\mathrm{\κ}}_{\mathrm{yy}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(y\right)}}{\∂y}\right),n^{\left(y\right)}=0,\±1,\±2L---\left(2\right)$

${\mathrm{\κ}}_{\mathrm{yx}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(y\right)}}{\∂x}\right),n^{\left(y\right)}=0,\±1,\±2L---\left(3\right)$

n ^(y)Be interference fringe progression, κ in (2) formula _YyBe the y durection component of specimen surface curvature, κ in (3) formula _YxIt is the rotational component of specimen surface curvature.

With two gratings axis half-twist around the vertical raster plane in the grating face, can get the component of specimen surface curvature x direction:

${\mathrm{\κ}}_{\mathrm{xx}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(x\right)}}{\∂x}\right),n^{\left(x\right)}=0,\±1,\±2L---\left(4\right)$

(4) κ in _XxBe the x durection component of specimen surface curvature, n ^(x)Be the interference fringe progression that obtains behind grating rotating 90 degree.

Just can be to the whole audience information of specimen surface curvature by (2), (3), (4) formula:

$\left\{\begin{array}{cc}{\mathrm{\κ}}_{\mathrm{xx}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(x\right)}}{\∂x}\right),& \\ {\mathrm{\κ}}_{\mathrm{yy}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(y\right)}}{\∂y}\right),& \begin{array}{c}{n}^{\left(x\right)}=0,\±1,\±2L\\ n^{\left(y\right)}=0,\±1,\±2L\end{array}\\ {\mathrm{\κ}}_{\mathrm{xy}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(x\right)}}{\∂y}\right)& \end{array}\right.---\left(5\right)$

(5) κ in the formula _XxBe the x durection component of specimen surface curvature, κ _YyBe the y durection component of specimen surface curvature, κ _XyBe specimen surface curvature rotational component, n ^(x)Representative is at the fringe order of x direction shear interference, n ^(y)Representative is compared with other curvature measurement method at the fringe order of y direction shear interference, and the advantage of this curvature measurement method is: realized that the curvature whole audience (obtains κ _Xx, κ _Yy, κ _XyThree components), online, real-time measurement, and be not subjected to vibration interference.

Obtained specimen surface curvature (κ by (5) formula _Xx, κ _Yy, κ _XyThree components), the assumed condition of Stoney formula is removed, the relation that obtains unequal stress in the film and curvature through more accurate analysis is shown in (6) formula:

$\left\{\begin{array}{c}{\mathrm{\σ}}_{\mathrm{rr}}^{\left(f\right)}+{\mathrm{\σ}}_{\mathrm{\θ\θ}}^{\left(f\right)}=\frac{E_s{h}_s^2}{6(1-v_s)h_f}[{\mathrm{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}}+\frac{1-v_s}{1+v_s}({\mathrm{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}}-\stackrel{\‾}{{\mathrm{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}}})]\\ {\mathrm{\σ}}_{\mathrm{rr}}^{\left(f\right)}-{\mathrm{\σ}}_{\mathrm{\θ\θ}}^{\left(f\right)}=-\frac{2E_f{h}_s}{3(1+v_f)}({\mathrm{\κ}}_{\mathrm{rr}}-{\mathrm{\κ}}_{\mathrm{\θ\θ}})\\ \mathrm{\τ}=\frac{E_s{h}_s^2}{6(1-v_s^2)}\frac{d}{\mathrm{dr}}({\text{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}})\end{array}\right.---\left(6\right)$

(6) in the formula,

Be respectively radial stress and the circumferential stress in the film, τ is the shearing stress between film and the basal body interface, E _f, v _fBe respectively the elastic modulus and the Poisson ratio of film, E _s, v _sBe respectively the elastic modulus and the Poisson ratio of matrix, h _f, h _sBe respectively film thickness and matrix thickness, κ _Rr, κ _{θ θ}Be respectively the radial component and the circumferential component of film matrix structure curvature, can obtain through coordinate conversion by curvature under the rectangular coordinate system in (5) formula.By (6) formula as can be known, as long as realize that the measurement of full field of film matrix structure curvature (is κ _Rr, κ _{θ θ}Measurement), just can realize the measurement of thin film non-uniform stress.

Ke Er magneto-optic (Kerr) effect according to the ferromagnetic thin film surface, on the ferromagnetic thin film surface after linearly polarized light incides magnetization, polarization state by the light beam of surface reflection changes, light intensity by the analyzing prism also changes, intensity variations and measured material magnetic induction density are proportional under first approximation, during actual measurement, measure reflective light intensity I by photoelectric detector 10, utilize the sample of the known magnetization character of standard to replace sample 3 again, record reflective light intensity I ' because the magnetization character of sample is known, by the magnetic induction density B of externally-applied magnetic field intensity H calculation sample ', the magnetic induction density of sample can calculate by (7) formula

$B=\frac{I}{I\′}B\′---\left(7\right)$

Obtain the magnetic induction density B of sample 3 thus, change externally-applied magnetic field intensity, measure the magnetic induction density of sample under different externally-applied magnetic field intensity, thereby draw the magnetic hysteresis loop of sample.

The magnetoelastic properties of described ferromagnetic thin film is online test method simultaneously, it is characterized in that: the non-homogeneous curvature of utilizing shear interference MEASUREMENTS OF THIN surface, by the calculated stress that concerns between curvature and the thin film non-uniform stress, utilize magneto-optical kerr (Kerr) effect on ferromagnetic thin film surface, measure the magnetic induction density of determining film from the film surface reflective light intensity.

The first laser instrument 1a of the present invention and the second laser instrument 1b adopt the different frequency light source;

The magnetoelastic properties of ferromagnetic thin film provided by the invention is online test method simultaneously, ferromagnetic thin film unequal stress light path is measured in this method utilization and two light paths of MEASUREMENTS OF THIN magnetic hysteresis loop light path are carried out online detection, and described thin film non-uniform stress is measured light path and comprised the first laser instrument 1a, the first beam expanding lens 2a, the first grating 4a, the second grating 4b, lens 5, filter screen 6 and CCD camera 7; Described MEASUREMENTS OF THIN magnetic hysteresis loop light path comprises the second laser instrument 1b, the second beam expanding lens 2b, polarizer 8, analyzer 9 and photoelectric detector 10, and its detection method comprises the steps:

A. utilize externally-applied magnetic field to make sample 3 magnetization, and record externally-applied magnetic field intensity H;

B. open the first laser instrument 1a, make light beam that first laser instrument sends by the first beam expanding lens 2a, and regulate the first beam expanding lens 2a, make the laser beam expanding that sends from first laser instrument and keep homogeneity;

C. the light beam irradiates after being restrainted by first beam expanding lens 2a expansion is passed through the first grating 4a, the second grating 4b, lens 5, filter screen 6 and CCD camera 7 to sample 3 surfaces successively from the specimen surface beam reflected;

D. the major axes orientation of the first grating 4a and the second grating 4b is arranged to vertical direction, adjusts the distance between lens 5, filter screen 6 and the CCD camera 7, obtain interference image clearly;

E. extract the interference fringe center line, calculate the fringe order variable gradient

With , n ^(y)Be interference fringe progression, pass through following formula:

${\mathrm{\κ}}_{\mathrm{yy}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(y\right)}}{\∂y}\right),$ ${\mathrm{\κ}}_{\mathrm{xy}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(y\right)}}{\∂y}\right)$

Calculate specimen surface y directional curvature κ _YyWith spin curvature κ _Xy, p is a grating constant in the following formula, Δ is two grating spaces;

F. with the first grating 4a and the second grating 4b in the grating face around the axis on vertical raster plane to the equidirectional half-twist, obtain interference fringe, extract the interference fringe center line, the fringe order number scale is made n ^(x), calculate the fringe order variable gradient

By following formula:

${\mathrm{\κ}}_{\mathrm{xx}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(x\right)}}{\∂x}\right)$

Calculate specimen surface x directional curvature κ _Xx

G. pass through the coordinate conversion formula with the curvature κ under the rectangular coordinate _Xx, κ _Yy, κ _XyConvert the curvature κ under the cylindrical coordinates to _Rr, κ _{θ θ}, pass through following formula:

$\left\{\begin{array}{c}{\mathrm{\σ}}_{\mathrm{rr}}^{\left(f\right)}+{\mathrm{\σ}}_{\mathrm{\θ\θ}}^{\left(f\right)}=\frac{E_s{h}_s^2}{6(1-v_s)h_f}[{\mathrm{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}}+\frac{1-v_s}{1+v_s}({\mathrm{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}}-\stackrel{\‾}{{\mathrm{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}}})]\\ {\mathrm{\σ}}_{\mathrm{rr}}^{\left(f\right)}-{\mathrm{\σ}}_{\mathrm{\θ\θ}}^{\left(f\right)}=-\frac{2E_f{h}_s}{3(1+v_f)}({\mathrm{\κ}}_{\mathrm{rr}}-{\mathrm{\κ}}_{\mathrm{\θ\θ}})\\ \mathrm{\τ}=\frac{E_s{h}_s^2}{6(1-v_s^2)}\frac{d}{\mathrm{dr}}({\text{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}})\end{array}\right.$

Calculate Obtain the unequal stress of sample, E in the following formula with τ _fBe the thin flexible film modulus, v _fBe the film Poisson ratio, E _sBe matrix elastic modulus, v _sBe the matrix Poisson ratio, h _fBe film thickness, h _sBe matrix thickness,

Be the radial stress in the film,

Be the circumferential stress in the film, τ is the shearing stress between film and the basal body interface, d (κ _Rr+ κ _{θ θ})/dr represents the radial derivative of principal curvatures sum;

H. open the second laser instrument 1b, the light beam that second laser instrument is sent passes through the second beam expanding lens 2b; And regulate the second beam expanding lens 2b and make the laser beam expanding that sends from second laser instrument and keep homogeneity;

I. after the light beam behind the second beam expanding lens 2b expansion bundle is by polarizer 8, become linearly polarized light, this linearly polarized light shines sample 3 surfaces, the light beam that reflects from specimen surface passes through photoelectric detector 10 again through analyzer 9, measures received beam intensity I by photoelectric detector;

J. utilize the sample of the known magnetization character of standard to replace sample 3, repeating step i records reflective light intensity I ' because the magnetization character of sample is known, by the magnetic induction density B of externally-applied magnetic field intensity H calculation sample ', the magnetic induction density of sample 3 can calculate by following formula

$B=\frac{I}{I\′}B\′$

Obtain the magnetic induction density B of sample 3;

K. change externally-applied magnetic field intensity H, repeating step i measures the reflective light intensity I of sample 3 under different externally-applied magnetic field intensity H, calculates the magnetic induction density B of sample under different externally-applied magnetic field intensity, draws the magnetic hysteresis loop of sample.

Claims (2)

1. the magnetoelastic properties of ferromagnetic thin film online test method simultaneously, it is characterized in that: ferromagnetic thin film unequal stress light path is measured in this method utilization and two light paths of MEASUREMENTS OF THIN magnetic hysteresis loop light path are carried out online detection, and described thin film non-uniform stress is measured light path and comprised first laser instrument (1a), first beam expanding lens (2a), first grating (4a), second grating (4b), lens (5), filter screen (6) and CCD camera (7); Described MEASUREMENTS OF THIN magnetic hysteresis loop light path comprises second laser instrument (1b), second beam expanding lens (2b), polarizer (8), analyzer (9) and photoelectric detector (10), and its detection method comprises the steps:

A. utilize externally-applied magnetic field to make sample (3) magnetization, and record externally-applied magnetic field intensity H;

B. open first laser instrument (1a), make light beam that first laser instrument sends by first beam expanding lens (2a), and regulate first beam expanding lens (2a), make the laser beam expanding that sends from first laser instrument and keep homogeneity;

C. the light beam irradiates after being restrainted by first beam expanding lens (2a) expansion is passed through first grating (4a), second grating (4b), lens (5), filter screen (6) and CCD camera (7) to sample (3) surface successively from the specimen surface beam reflected;

D. the major axes orientation of first grating (4a) and second grating (4b) is arranged to vertical direction, adjusts the distance between lens (5), filter screen (6) and the CCD camera (7), obtain interference image clearly;

E. extract the interference fringe center line, calculate the fringe order variable gradient

With

N (y) is an interference fringe progression, passes through following formula:

${\mathrm{\κ}}_{\mathrm{yy}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(y\right)}}{\∂y}\right),$ ${\mathrm{\κ}}_{\mathrm{xy}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(y\right)}}{\∂y}\right)$

Calculate specimen surface y directional curvature κ _YyWith spin curvature κ _Xy, p is a grating constant in the following formula, Δ is two grating spaces;

F. with first grating (4a) and second grating (4b) in the grating face around the axis on vertical raster plane to the equidirectional half-twist, obtain interference fringe, extract the interference fringe center line, the fringe order number scale is made n ^(x), calculate the fringe order variable gradient By following formula:

${\mathrm{\κ}}_{\mathrm{xx}}\≈\frac{p}{2\mathrm{\Δ}}\left(\frac{{\∂n}^{\left(x\right)}}{\∂x}\right)$

Calculate specimen surface x directional curvature κ _Xx

G. pass through the coordinate conversion formula with the curvature κ under the rectangular coordinate _Xx, κ _Yy, κ _XyConvert the curvature κ under the cylindrical coordinates to _Rr, κ _{θ θ}, pass through following formula:

$\left\{\begin{array}{c}{\mathrm{\σ}}_{\mathrm{rr}}^{\left(f\right)}+{\mathrm{\σ}}_{\mathrm{\θ\θ}}^{\left(f\right)}=\frac{E_s{h}_s^2}{6(1-v_s)h_f}[{\mathrm{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}}+\frac{1-v_s}{1+v_s}({\mathrm{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}}-\stackrel{\‾}{{\mathrm{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}}})]\\ {\mathrm{\σ}}_{\mathrm{rr}}^{\left(f\right)}-{\mathrm{\σ}}_{\mathrm{\θ\θ}}^{\left(f\right)}=-\frac{{2E}_f{h}_s}{3(1+v_f)}({\mathrm{\κ}}_{\mathrm{rr}}-{\mathrm{\κ}}_{\mathrm{\θ\θ}})\\ \mathrm{\τ}=\frac{E_s{h}_s^2}{6(1-v_s^2)}\frac{d}{\mathrm{dr}}({\mathrm{\κ}}_{\mathrm{rr}}+{\mathrm{\κ}}_{\mathrm{\θ\θ}})\end{array}\right.$

Calculate Obtain the unequal stress of sample, E in the following formula with τ _fBe the thin flexible film modulus, v _fBe the film Poisson ratio, E _sBe matrix elastic modulus, v _sBe the matrix Poisson ratio, h _fBe film thickness, h _sBe matrix thickness,

Be the radial stress in the film,

Be the circumferential stress in the film, τ is the shearing stress between film and the basal body interface, d (κ _Rr+ κ _{θ θ})/dr represents the radial derivative of principal curvatures sum;

H. open second laser instrument (1b), the light beam that second laser instrument is sent passes through second beam expanding lens (2b); And regulate second beam expanding lens (2b) and make the laser beam expanding that sends from second laser instrument and keep homogeneity;

I. after the light beam behind second beam expanding lens (2b) the expansion bundle is by polarizer (8), become linearly polarized light, this linearly polarized light shines sample (3) surface, the light beam that reflects from specimen surface passes through photoelectric detector (10) again through analyzer (9), measures received beam intensity I by photoelectric detector;

J. utilize the sample of the known magnetization character of standard to replace sample (3), repeating step i records reflective light intensity I ' because the magnetization character of sample is known, by the magnetic induction density B of externally-applied magnetic field intensity H calculation sample ', the magnetic induction density of sample (3) can calculate by following formula

$B=\frac{I}{I\′}B\′$

Obtain the magnetic induction density B of sample (3);

K. change externally-applied magnetic field intensity H, repeating step i measures the reflective light intensity I of sample (3) under different externally-applied magnetic field intensity H, calculates the magnetic induction density B of sample under different externally-applied magnetic field intensity, draws the magnetic hysteresis loop of sample.

2. according to the magnetoelastic properties while online test method of the described a kind of ferromagnetic thin film of claim 1, it is characterized in that: first laser instrument (1a) and second laser instrument (1b) adopt the laser instrument of different frequency.

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