WO2005001495A1

WO2005001495A1 - Magnetization observing method and magnetization observing instrument

Info

Publication number: WO2005001495A1
Application number: PCT/JP2003/008096
Authority: WO
Inventors: Toshiaki Nagai
Original assignee: Fujitsu Limited
Priority date: 2003-06-26
Filing date: 2003-06-26
Publication date: 2005-01-06
Also published as: JP4247230B2; JPWO2005001495A1

Abstract

A magnetization observing instrument wherein a magnetic field of a specified magnetic field strength, a first magnetic field strength less than the specified magnetic field strength, and a second magnetic field strength greater than the specified magnetic field acts on a magnetic body, the measurement values of the first to third values of the respective magnetic field strengths are measured, the magnetic walls (42, 42a) move depending on the variation of the magnetic field, the first to third measurement values are added with weights of a ratio 2:-1:-1, a magnetization vector is left in the range where the magnetic walls move, the noise is cancelled on the basis of weighting under the assumption that the first to third measurement values evenly include noise, the magnetization outside the range where the magnetic walls move is cancelled by the measurement values, only the magnetic walls are conspicuous, thus a magnetic domain can be clearly visualized irrespective of the surface state of the magnetic body, and the directions of magnetization of the adjacent magnetic domains on both sides of a magnetic wall can be discriminated from each other. When the direction of magnetization is thus visualized, the direction of magnetization in a magnetic domain can be relatively easily determined.

Description

Magnetization observation method and magnetization observation device

The present invention relates to a magnetization observation method and a magnetization observation device capable of observing a magnetic domain structure of a magnetic material, and more particularly to an optical system for guiding light to a magnetic material, and detection of a magneto-optical effect based on ^ returned from the magnetic material. The present invention relates to a magnetization observation device including a light receiving element that outputs a detection signal for specifying a value. ,

In the specification and the claims, a positive value and a negative value are specified for the magnetic field strength in accordance with a prescribed direction. Similarly, the field strength shall include a “0 (zero)” value. Background art

The so-called Kerr microscope is widely known. In this Kerr microscope, light is irradiated to a magnetic substance in a predetermined polarization state. The light reflected from the magnetic material causes a change in the polarization state, such as rotation of the polarization plane and an increase or decrease in the reflectance, based on the magnetic Kerr effect. The magnetization is detected based on this change in the polarization state.

The surface state of the magnetic material affects the polarization state and the reflectance. If the surface condition of the magnetic material is poor, rotation of the polarization plane and an increase or decrease in the reflectivity are caused irrespective of the magnetic Kerr effect. These changes in polarization often exceed the changes in polarization produced by the magnetic Kerr effect. In these cases, the domain structure established in the magnetic material cannot be clearly observed. There is a need to find a way to clearly detect the magnetic domain structure of the magnetic material regardless of the surface condition.

Patent Document 1

Japanese Unexamined Patent Publication No. Hei 5—2 9 6 8 4 1

Patent Document 2

Japanese Unexamined Patent Publication No. Hei 5—2 1 5 8 2 8

Patent Document 3 Japanese Unexamined Patent Publication No. Hei 2-0 4 0 5 7 9

Patent Document 4

Japanese Unexamined Patent Publication No. Hei 2-0 4 580

Patent Document 5

Japanese Unexamined Patent Publication No. Hei 6—0 2 7 210

Non-patent document 1

K. Shirae, K. Sugiyama, 'Ά CCD image sensor and a microcomputer make magnetic domain observation clear and convenient "Journal of Applied Physics, 1982, 53 (11), pp8380-8382

Non-patent document 2

DA Herman, Jr., et al. "Bloch lines, cross ties, and taffy in permalloy (invited)" Journal of Applied Physics, 1987, 61 (8), pp4200-4206

Non-patent document 3

Mark E. Re, et al. "Magneto-optic investigation of thin-film recording heads" Journal of Applied Physics, 984, 55 (6), pp2245-2247

Non-patent document 4

Toshiaki Nagai et al., "Method for Measuring Perpendicular and In-Plane Magnetization Components Using Broadband Kerr Microscope," Proceedings of the 26th Annual Meeting of the Japan Society of Applied Magnetics, 2002, p. 398

The present invention has been made in view of the above situation, and has as its object to provide a magnetization observation method and a magnetization observation apparatus that can greatly contribute to observation of a clear magnetic domain structure regardless of the surface state of a magnetic body. I do. An object of the present invention is to provide a magnetization observation method and a magnetization observation apparatus which are greatly useful for specifying not only the position of a domain wall but also the direction of magnetization in an adjacent magnetic domain.

In order to achieve the above object, according to the first invention, a magnetic field strength H specified for a magnetic body along a predetermined direction. Applying a magnetic field in the step, detecting the magnetization of the magnetic material based on the magneto-optical effect, and specifying the first detected value of the magnetic field, and a specified magnetic field strength H. 1st magnetic field strength H! The magnetization of the magnetic material is detected in the magnetic field of And the specified magnetic field strength H. A step of detecting the magnetization of magnetic material element, identifying a third detection value of the magnetization in a magnetic field of a larger second magnetic field strength H ₂ than 2: - 1: - first based on the weighting scheme for 1, Adding a second and a third detection value.

When the magnetic field acts on the magnetic material at the first magnetic field strength H, the domain wall moves in the magnetic material as the magnetic field decreases. When a magnetic field in the second magnetic field strength H ₂ is applied to the magnetic domain wall with decreasing magnetic field in the magnetic body moves. Such movement of the domain wall generates a rotation of magnetization at each measurement point (observation point). When the first, second, and third detection values are added by the weighting described above, the magnetization vector remains in the domain wall movement range. Since it is assumed that the first, second, and third detection values include noise equally, the noise is canceled based on the weight. Pure magnetization vectors are specified. On the other hand, in a region outside the domain wall movement range, the magnetization is canceled by the detected value. In this way, only the domain wall is highlighted. Therefore, a clear magnetic domain structure can be visualized regardless of the surface state of the magnetic material.

Moreover, the direction of magnetization is distinguished between the magnetic domains across the domain wall. If the magnetization direction force S is visualized, the magnetization direction in the magnetic domain can be specified relatively easily. For visualization, the pixels may be color-coded based on the result of the aforementioned addition. In realizing the weighting, between the output value t (H _Q ), the first detection value s (H ₀ ), the second detection value s (H i), and the third detection value s (H ₂ ),

[Formula 1]

^ ₀ ) = 2- ^ ₀ )-[^) + ^ 2)]

= [^ ₀ )-^)] + [^ θ)-^ 2)] ... hi).

When observing a magnetic material, it is desired that saturation of magnetization in the magnetic material be avoided. If the magnetic material is saturated in the magnetic material, the structure of the magnetic domain will be destroyed. It is expected that the connection relationship between domain walls will change. The first magnetic field strength may be set to a value sufficiently larger than the magnetic field strength that induces the saturation of the magnetization. Second magnetic field strength H. Should be set to a value sufficiently smaller than the magnetic field strength that induces magnetization saturation. Yes. Thus it is set first magnetic field strength and the second magnetic field strength H ₂ is connected relation of a domain wall between which is established a magnetic body is expected to be reliably maintained. However, the first magnetic field strength H is set to a value that produces a difference between the first detection value and the second detection value. Similarly, the second magnetic field strength H ₂ is set to a size that produces phase differences between the first detection value and the third detection value. If the movement of the domain wall is generated in this way, the domain wall can be reliably detected.

In realizing the above-described magnetization observation method, a magnetization observation apparatus such as a force microscope, for example, uses a specified magnetic field strength, a first magnetic field strength smaller than the specified magnetic field strength, and a larger magnetic field strength than the specified field strength. A magnetic field generating mechanism for generating a magnetic field at the second magnetic field strength; an optical system for guiding light to a magnetic material exposed to the magnetic field generated by the magnetic field generating mechanism; and a specified magnetic field strength and first and second magnetic field strengths. When a magnetic field is applied, a light-receiving element that outputs a detection signal that specifies the corresponding first, second, and third detection values based on the magneto-optical effect of the magnetic body, and a light-receiving element that is connected to the light-receiving element; And a processor that adds the first, second, and third detection values based on the weighting of one.

In addition, the above-described magnetization observation method may be realized by a software program, for example. Such software programs, for example, have a specified magnetic field strength H Obtaining a first detection signal generated based on a magnetic field of a magnetic substance disposed in the magnetic field of the specified magnetic field strength; Obtaining a second detection signal generated based on the magnetization of a magnetic body disposed in a magnetic field having a first magnetic field strength smaller than the specified magnetic field strength H; A step of acquiring a third detection signal generated based on the magnetization of the magnetic body disposed in the larger second magnetic field strength of H ₂ in a magnetic field than, 2: - 1: - on the basis of the first weighting, first, The step of adding the detected values of the magnetization specified by the second and third detection signals may be executed by the processor. The software program may be stored in a specific storage device, or may be stored on a portable recording medium such as a compact disc (CD) or a digital video disc (DVD).

According to the second invention, a step of applying a magnetic field that changes in the first magnetic field strength range smaller than the specified magnetic field strength to the magnetic body, and the magneto-optical effect of the magnetic body during the change of the magnetic field within the first magnetic field strength range Detecting the presence or absence of a change in the magnetic field based on the magnetic field; and applying a magnetic field that changes in a second magnetic field strength range larger than a specified magnetic field strength to the magnetic body. Detecting the presence or absence of a change in magnetization based on the magneto-optical effect of the magnetic substance during a change in the magnetic field within the magnetic field strength range.

In general, when the magnetic field strength of the magnetic field changes, the magnetic material expands or contracts in the magnetic domain. As a result, the domain wall moves. When a particular measurement point is crossed by a domain wall during a change in the magnetic field, the direction of magnetization rotates at that measurement point. Therefore, if a change in magnetization is detected along with a change in the magnetic field, the position of the domain wall can be specified.

Now, assume a measurement point inside a specific magnetic domain. As the domain shrinks, its measurement point crosses the domain wall. The rotation of the magnetization is detected. On the other hand, even if the magnetic domain expands, the rotation of magnetization is not detected at the measurement point. In other words, when the change in magnetization is detected in the first magnetic field strength range and when the change in magnetization is detected in the second magnetic field strength range, the relationship between the movement of the domain wall and the increase and decrease of the magnetic field must be distinguished. Can be. In this way, information about the direction of magnetization in each magnetic domain can be obtained.

In detecting the presence or absence of a change, the magnetic field strength may be increased in the first and second magnetic field strength ranges. In this case, an increase in magnetization corresponding to a change in magnetization may be detected. A differential value may be specified based on a change in magnetization when detecting an increase in the magnetic field. In identifying the differential value, the magnetization observation method includes, for example, a step of discretely increasing the magnetic field strength in the first and second magnetic field strength ranges, and a magnetization of the magnetic material based on the magneto-optical effect for each magnetic field strength. And a step of calculating the magnetization change value by subtracting the previous detection value from the current detection value and detecting the magnetization detection value for each magnetic field strength.

In addition, when detecting the presence or absence of the change, the magnetic field strength may be reduced in the first and second magnetic field strength ranges. In this case, it is sufficient that the decrease in the magnetic field corresponding to the change in the magnetization is detected. In detecting the decrease in the magnetization, the differential value may be specified based on the change in the magnetization. In identifying the differential value, this type of magnetization observation method includes a step of discretely reducing the magnetic field strength in the first and second magnetic field strength ranges, and a method of magnetizing the magnetic material based on the magneto-optical effect for each magnetic field strength. It is sufficient to include a step of detecting magnetization and specifying a detection value of magnetization for each magnetic field intensity, and a step of calculating a change value of magnetization by subtracting a previous detection value from a current detection value.

To realize the magnetization observation method described above, a magnetization observation device such as a force microscope was used. For example, the position is generated by a magnetic field generating mechanism that generates a magnetic field that changes in a first magnetic field strength range smaller than a specified magnetic field strength and a second magnetic field strength range larger than the specified magnetic field strength, and a magnetic field generating mechanism. An optical system that guides light to a magnetic body exposed to a magnetic field, a light receiving element that receives light returning from the magnetic body, and a light receiving element that is connected to the light receiving element to change the first magnetic field intensity range and to change the second magnetic field intensity. A processor may be provided for detecting the presence or absence of a change in magnetization based on the magneto-optical effect of the magnetic substance during the change of the range.

In addition, the above-described magnetization observation method may be realized by, for example, a software program. Such a software program includes, for example, a step of obtaining a first detection signal generated based on the magnetization of a magnetic substance arranged in a magnetic field that changes in a first magnetic field strength range smaller than a specified magnetic field strength. Detecting the presence or absence of a change in magnetization based on the first detection signal; and generating the magnetic field based on a magnetic field of a magnetic substance arranged in a magnetic field that changes in a second magnetic field strength range larger than a specified magnetic field strength. The step of obtaining the second detection signal and the step of detecting the presence or absence of a change in magnetization based on the second detection signal may be performed by the processor. The software program may be stored in a specific storage device, or may be stored on a portable recording medium such as a compact disc (CD) or a digital video disc (DVD).

According to the third aspect, a step of causing the magnetic body to apply a magnetic field that changes at a specific cycle based on the waveform signal, and a step of detecting the magnetization of the magnetic body based on the magneto-optical effect and specifying a detected value of the magnetization Multiplying the specified detection value by a numerical value that periodically changes at twice the frequency of the waveform signal while synchronizing with the waveform signal in a specific phase relationship. Is provided.

In general, when the magnetic field strength of the magnetic field changes, the magnetic material expands or contracts in the magnetic domain. As a result, the domain wall moves. When a specific measurement point is traversed by a domain wall during a change in the magnetic field, the direction of the magnetization rapidly turns at that measurement point. Therefore, if the sudden change of the magnetic field is detected along with the change of the magnetic field, the position of the domain wall can be specified. At this time, the change in the magnetization can be emphasized by the product of the detected value of the magnetization and the above-mentioned numerical value. In addition, when the numerical value periodically changes at twice the frequency of the waveform signal, a different sign (10,-) is specified in the product according to the relationship between the moving direction of the domain wall and the increase / decrease of the magnetic field. Can be. In this way, the detected value of magnetization is visualized based on the calculation result. 200

If so, the position of the domain wall can be specified. Moreover, the direction of magnetization in the magnetic domain can be estimated relatively easily.

Such a magnetization observation method may further include a step of performing an integration process on a multiplication result of the detected value and the numerical value. According to such an integration process, a change in magnetization can be reliably detected. The phase indicating the maximum value and the minimum value of the waveform signal may coincide with the phase indicating either the maximum value or the minimum value of the numerical value. According to such a phase difference, a change in the magnetization can be reliably specified.

The detection value may be subjected to a differentiation process prior to the multiplication with the above numerical value. According to such a differentiation process, a change in magnetization can be detected more reliably. However, in this case, it is desired that the phase indicating the maximum value and the minimum value of the waveform signal coincide with the phase indicating the intermediate value between the maximum value and the minimum value in a numerical value.

In realizing the above-described magnetization observation method, a magnetization observation device such as a Kerr microscope uses, for example, a magnetic field generation mechanism that generates a magnetic field that changes at a specific cycle based on a waveform signal, and a magnetic field generated by the magnetic field generation mechanism. An optical system that guides light to the exposed magnetic material, a light-receiving element that outputs a detection signal that specifies a detection value based on the light that returns from the magnetic material, and a specific phase relationship with the waveform signal that is connected to the light-receiving element And a multiplier for multiplying the detection signal by a periodic signal that periodically changes at twice the frequency of the waveform signal while synchronizing. In order to implement the integration process, a one-pass filter may be connected to the multiplier. In realizing the differential processing, an eight-pass filter may be arranged between the multiplier and the light receiving element. Brief Description of Drawings

FIG. 1 is a block diagram schematically showing a structure of a Kerr microscope according to the first embodiment of the present invention.

FIG. 2 is an enlarged plan view schematically showing the structure of the polarization distribution control mechanism.

FIG. 3 is a conceptual diagram schematically showing the structure of a magnetic domain of a magnetic body.

FIG. 4 is a flowchart showing the processing operation of the processor (CPU) in observing Gyidani.

5A to 5F schematically show the principle of the processing operation when observing clockwise return magnetic domains. FIG.

6A to 6F are conceptual diagrams schematically showing the principle of the processing operation in observing the counterclockwise return magnetic domain.

7A to 7F are conceptual diagrams schematically showing processing operations according to a comparative example in observing clockwise return magnetic domains.

8A to 8F are conceptual diagrams schematically showing a processing operation according to a comparative example when observing a counterclockwise reflux zone. .

FIG. 9 is a flowchart showing a processing operation according to another specific example in observing the magnetization.

10A to 10C are conceptual diagrams schematically showing the principle of the processing operation.

FIGS. 11A and 11B are graphs showing the change in magnetization observed at a particular measurement point during an increase in magnetic field strength. '

FIGS. 12A and 12B are graphs showing the relationship between the increase in the magnetic field strength and the difference between the detected values.

Figures 13A and 13B are graphs showing the change in magnetization observed at a particular measurement point during a decrease in magnetic field strength.

FIGS. 144 and 148 are graphs showing the relationship between the decrease in the magnetic field strength and the difference between the detected values.

FIGS. 15A and 15B are graphs showing changes in detection values detected at specific measurement points while the magnetic field strength is increasing or decreasing.

FIG. 16 is a block diagram schematically showing a structure of a Kerr microscope according to the second embodiment of the present invention.

FIGS. 17A and 17B are graphs showing the relationship between the magnetic field that changes based on the first frequency and the magnetization.

FIGS. 18A and 18B are graphs showing the relationship between the magnetization that changes based on the first frequency and the waveform signal of the second frequency.

FIG. 19 is a block diagram schematically showing a structure of a force microscope according to the third embodiment of the present invention.

Fig. 2 OA and Fig. 20B show the detected value of magnetization after differential processing and the phase difference of 90 °. 6 is a graph showing a relationship with a signal waveform of a first frequency that changes in FIG.

FIGS. 21A and 21B are graphs showing the relationship between the detected value of the magnetization after the differential processing and the signal waveform of the second frequency that changes with a phase difference of 90 °. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 schematically shows the structure of a force microscope according to a first embodiment of the present invention. This force—the microscope 1 1 has a movable stage 1 2. For example, a support surface 13 extending along one horizontal plane is defined on the movable stage 12. The object to be measured, ie, the magnetic body 14 is received on the support surface 13. The movable stage 12 can move within at least one horizontal plane. The movement of the movable stage 12 is controlled based on an electric signal supplied from the stage driver 15.

A magnetic field generating mechanism 16 is associated with the movable stage 12. The magnetic field generating mechanism 16 may be composed of, for example, a pair of electromagnets 17. The electromagnets 17 and 17 generate the magnetic field 19 with a desired magnetic field strength according to the magnitude and direction of the current supplied from the electromagnet driver 18. By the action of such a magnetic field 19, a magnetic flux flows through the magnetic body 14 on the worship surface 13 along a prescribed direction.

The Kerr microscope 11 further includes a light source 21. For example, a laser diode that outputs a laser beam having a wavelength of 400 nm may be used as the light source 21. The laser beam is output toward the support surface 13 of the movable stage 12. The laser beam establishes, for example, linearly polarized light.

An optical system 22 is arranged between the light source 21 and the movable stage 12. The optical system 22 includes, for example, an objective lens 23 facing the movable stage 12. A beam splitter 24 is disposed between the light source 21 and the objective lens 23, for example. The laser beam output from the light source 21 passes through the beam splitter 24. After that, the laser beam is applied to the magnetic body 14 from the objective lens 23. The objective lens 23 forms a minute beam spot on the surface of the magnetic body 14. In this way, the laser beam is guided to the magnetic body 14 with the designated plane of polarization. The laser beam reflects off the surface of the magnetic body 14. The laser beam is again split from the objective lens 23 by the beam splitter 2. Guided to 4. At this time, the above-described magnetic field generation mechanism 16 may be associated with the objective lens 23.

A polarizing beam splitter 25 is opposed to the beam splitter 24. The laser beam returning from the magnetic body 14 is reflected at the beam splitter 24. The laser beam is directed from beam splitter 24 to polarizing beam splitter 25. The polarization beam splitter 25 splits the laser beam with polarization planes orthogonal to each other.

Behind the polarizing beam splitter 25, light receiving elements, that is, photodetectors 26 and 26 are arranged. The laser beam decomposed by the polarization beam splitter 25 is collected, and then detected by the photodetector 26 for each polarization plane. Thus, the laser beam is converted into an electric signal for each polarization plane.

A differential amplifier 27 is connected to the photodetectors 26 and 26. The differential amplifier 27 derives the difference between the two electrical signals. The rotation of the polarization plane is detected based on the difference.

An analog / digital converter (AZD converter) 28 is connected to the differential amplifier 27. The AZD converter 28 generates a digital signal from the analog electric signal output from the differential amplifier 27. A computer device 29 is connected to the AZD converter 28. The computer device 29 includes a processor (CPU) 31 that acquires a digital signal, that is, a detection signal, supplied from the AZD converter 28. The operation of the CPU 31 is realized based on, for example, a software program stored in the storage device 32. When a predetermined software program is executed, the CPU 3.1 supplies a predetermined command signal to the stage driver 15 and the electromagnet driver 18. As the storage device 32, an FDD (flexible disk drive), an HDD (hard disk drive), a CD (compact disk) drive, a DVD (digital video disk) drive, a memory, or the like may be used. The display device 33 is connected to the computer device 29. Images and texts can be displayed on the screen of the display device 33. The CPU 31 can draw an image of the magnetic domain on the screen of the display device 33 based on the detection signal described above.

In this force microscope 11, the beam splitter 24 and the polarizing beam splitter are used. Between 25, a polarization distribution control mechanism 34 is incorporated. As the polarization distribution control mechanism 34, as shown in FIG. 2, a split half-wave plate 35 composed of, for example, four half-wave plates 35a to 35d may be used. The split half-wave plate 35 is composed of first and second half-wave plates 35a and 35b joined to each other on a horizontal plane, and third and fourth half-wave plates 35 and 35b joined to each other on a vertical plane. Half-wave plates 35 c and 35 d are provided. In the first and third half-wave plates 35a and 35c, the neutral axis azimuth is set to −22.5 °. On the other hand, in the second and fourth half-wave plates 35b and 35d, the neutral axis azimuth is set to + 22.5 °.

In such a split half-wave plate 35, the first and third half-wave plates 35a and 35c pass (1-45- δ °) is established. Similarly, the second and fourth half-wave plates 35 b and 35 d establish a polarization of (45— (5 °). As a result, the first and third half-wave plates 35 a and 3 A 90 ° shift can be created between 5c and the second and fourth half-wave plates 35b, 35d.Accordingly, according to the force microscope 11, for example, When the laser beam 36 is transmitted along the boundary between the second half-wave plate 35a and the second half-wave plate 35b, the first effect is canceled out as much as possible, and thus the in-plane magnetization X component is detected. (4) When the laser beam 37 passes along the boundary between the half-wave plates 35c and 35d, the effect is canceled out as much as possible, and the in-plane magnetization y component is thus detected. If the light passes through only the second half-wave plate 35b without touching, the perpendicular magnetization component can be detected.

Now, assume a case where the structure of a magnetic domain is observed based on the detection of the in-plane magnetization X component of the thin magnetic material 14. In the magnetic body 14, for example, as shown in FIG. 3, domain walls 42a and 42 are established between the adjacent magnetic domains 41a, 41b and 41.

In observation, first, the CPU 31 sets a plurality of measurement points on the surface of the magnetic body 14. As is clear from FIG. 3, the measurement points are arranged, for example, in a matrix LXM. The measurement point may be specified in accordance with, for example, plane coordinates (X, Y) preset on the support surface 13. The center of the beam spot is aligned with the position (X, Y) of the measurement point. The intervals between adjacent measurement points may be set to be uniform. The beam spots may be overlapped or separated from each other at adjacent measurement points. The CPU 31 implements a processing operation according to a predetermined software program. As shown in FIG. 4, when the observation is started, the CPU 31 performs initialization in step S1. In step S2, the magnetic field strength H specified for the magnetic body 14 based on the processing operation of the CPU 31. A magnetic field 19 is applied. When applying a magnetic field, the CPU 31 generates a predetermined command signal. The generated command signal specifies the current value and direction of the current. The electromagnet driver 18 supplies current to the electromagnets 17 and 17 based on such a command signal. Magnetic field strength H by the action of electromagnets 17 and 17. A magnetic field 19 is generated. The generated magnetic field 19 acts on the magnetic body 14 on the stage 12.

Here, the magnetic field strength H. Can be defined as positive and negative values along a specified direction. In other words, when the magnetic field strength H ₀ is set to a negative value (H. <0), the direction of the magnetic field 19 is reversed. As the negative value decreases, the magnetic field after reversal increases. Moreover, the magnetic field strength H ₀ includes a “0 (zero)” value. Magnetic field strength H. In

When the “0” value is set, no magnetic field is generated from the electromagnets 17 and 17. However, in this specification, any of them is expressed as a “magnetic field” of the magnetic field strength H _Q. The magnetic field strength H ₀ may be set to an appropriate value.

In step S3, the CPU 31 obtains a first detection value _sk (H.). Bicycloalkyl one beam spot when the acquisition of the first detection value s _k (H ₀₎ is positioned at a position (X i, Y j). The laser beam is reflected from the surface of the magnetic body 14. In the laser beam, the rotation of the polarization plane is caused by the action of the magnetic Kerr effect of the magnetic body 14. The rotation of the plane of polarization is quantified by the differential amplifier 27. Thus, the AZD converter 28 outputs the first detection value _sk (H.) with a size corresponding to the rotation amount of the polarization plane. The CPU 31 records the first detection value _sk (H.) in the storage device 32, for example.

In step S4, the magnetic field strength H is set based on the processing operation of the CPU 31. A magnetic field 19 is applied to the magnetic body 14 with a smaller magnetic field strength より_λ «H ₀ ). As described above, upon application of the magnetic field, the CPU 31 generates a predetermined command signal. The electromagnet dryno 18 supplies current to the electromagnets 17 and 17 based on such a command signal. The electromagnets 17 and 17 generate a magnetic field 19 having a magnetic field strength. The generated magnetic field 19 acts on the magnetic body 14 on the stage 12. As described above, the magnetic field strength Hi may be set to a negative value (1 ^ <0) or a “0 (zero)” value. At 5, the CPU 31 acquires the second detection value _sk (^). Beam spot when the acquisition of the second test detection value s _k (Hi) is held in position (XY j). AZD converter 28 outputs the second detection value s _k (Η _α) in the magnitude corresponding to the amount of rotation of the polarization plane. The CPU 31 records the second detection value s _k (H j) in the storage device 32, for example. If the direction of magnetization does not change in the laser spot, the second detected value s _k (H is equal to the first detected value s _k (H ₀ ).

In step S6, the magnetic field strength H is set based on the processing operation of the CPU 31. A magnetic field 19 is applied to the magnetic body 14 with a magnetic field strength H ₂ (> H ₀ ) higher than that. As described above, upon application of the magnetic field, the CPU 31 generates a predetermined command signal. The electromagnet driver 18 supplies current to the electromagnets 17 and 17 based on the command signal. The electromagnets 17 generate a magnetic field 19 of magnetic field strength. The generated magnetic field 19 acts on the magnetic body 14 on the stage 12. As before, the magnetic field strength Eta ₂ is a negative value (Eta ₂ ° 0) or "0" (zero) value may be set.

In CPU 3 1 Step S 7 followed to obtain a third detection value s _k (H _2). Third beam spot when the acquisition of test detection value s _k (H ₂₎ is held in position (X i, Y j). The AZD converter 28 outputs the third detection value _sk (H ₂ ) with a magnitude corresponding to the amount of rotation of the polarization plane. The CPU 31 records the third detection value s _k (H ₂ ) in the storage device 32, for example. If the direction of magnetization does not change in the laser spot, the third detection value _sk (H ₂ ) matches the first detection value _sk (H.) and the second detection value _sk (H _x ) .

First detection value s _k (H.), measurement of the second detection value s _k (H _x) and the third detection value s _k (H ₂₎ is repeated at specified times N. Until the completion of the specified number N is confirmed in step S8, the storage device 32 stores N first detection values s _k (H ₀ ) and N second detection values s _k (H _x ) N Is recorded as the third detection value s _k (H ₂ ). Thus the first detection value s _k (H.), the measurement of the second detection value s _k (Hi) and the third detection value s _k (H ₂₎ is complete, the processing operation CPU 3 1 is step S 9 Move to

In step S 9, CPU 31 is first detected value s _k (H ₀₎ of the N acquired, the N of the second detection value s _k (kappa,) and Ν pieces of the third detection value s _k (H ₂ ) Based on the output value t

(H ₀ ) is calculated. 2: The first detection value s _k (H ₀ ), the second detection value s _k (H and the third detection value s _k (H ₂ ) are added based on the weighting of 1: 1. For example, the following equation may be used.

[Formula 2]

^ ο) = ^ · ∑ {2 · s _k (H ₀ )-[ _¾ (^) + s _k H ₂ )]}

■ N = ι

However, similar results can be obtained even if the following equation is used.

[Equation 3] + s _k (H ₂ )]} .. 3)

Here, any numerical value may be inserted in the coefficient. The principle of calculation will be described later.

Then, CPU 31 at step S 10, to implement the display processing based on the output value t (H _0). The CPU 31 determines the type of the pixel based on the output value t (H ₀ ). The pixels may be color-coded based on the magnitude of the output value t (H ₀ ), for example. Thus the magnetization measured at position (X i, Yj) is visualized.

In the following step S11, it is determined whether or not pixels have been determined at all positions (Xi, Yj) in the y column. If undetermined pixels remain, the processing operation of the CPU 31 returns to step S2. Each time the processing operation of steps S2 to S10 is repeated, the X coordinate value is added. Thus, pixels are determined at all positions (X i, Yj) in the y column. When all pixels are determined in the y-th column, the processing operation shifts to Step S12.

In step S12, it is determined whether the processing operations in steps S2 to S11 have been performed for all y columns. If the unprocessed y columns remain, the processing operation of the CPU 31 returns to step S2. Each time the processing operations of steps S2 to S11 are repeated, the y coordinate value is added. Thus, the pixel is determined at every position (X i, Y j) of the matrix LXM. The domain wall 42a is displayed on the screen of the display device 33,

42 is drawn. Here, the principle of [Equation 2] will be briefly described. The specified field strength H, as shown in Figure 5A. When the magnetic field 19 acts on the magnetic body 14 in the magnetic field 14, magnetic domains 41a, 41b, and 41 are established in the magnetic body 14. Next, the magnetic field strength H. When the magnetic field 19 acts on the magnetic body 14 at a smaller magnetic field strength Hi, as shown in FIG. 5B, in the magnetic body 14, the magnetic domain 41b expands as the magnetic field 19 decreases. Domain 41a shrinks. The movement of the domain walls 42a, 42 is caused. In particular, if the magnetic domain 41 a, 4 lb establishes magnetization parallel to the specified direction (x-axis) or antiparallel magnetization, the domain wall 42 a parallel to the specified direction is almost parallel While maintaining the position, move parallel to the y-axis perpendicular to the specified direction. Here, the decrease in the magnetic field 19 includes an increase in the magnetic field in the opposite direction to the prescribed direction. Conversely, magnetic field strength H. When a magnetic field 19 is applied to the magnetic substance 1 4 a large magnetic field strength H ₂ than, as shown in Figure 5C, entailment domain 41 a to an increase in the magnetic body 14 in the magnetic field 19 will expand. Domain 41b shrinks. Thus, the movement of the domain walls 42a and 42 is caused. The domain wall 42a moves in parallel to the y-axis orthogonal to the prescribed direction while maintaining the substantially parallel posture. Here, the increase in the magnetic field 19 includes a decrease in the magnetic field in the opposite direction to the prescribed direction.

When the second detection value s _k (H ^ and the third detection value s _k (H ₂ ) are added, for example, as shown in FIG. 5D, individual positions (X i, Yj), the magnetization vectors of different directions are added.Especially, in the movement range of the domain wall 42a, the antiparallel magnetic waves are virtually canceled at each position (Xi, Yj) ( (Mg = 0) In the region outside the moving range of the domain walls 42 and 42a, the magnetization vectors of the same direction are added for each position (Xi, Yi).

The second detection value s _k and (Hi) and the third detection value s _k (H ₂₎ is equal when the direction of no磁I匕M g involved in the intensity of the magnetic field intensity H There H ₂ does not change. The average value of the second and third detection values s _k (H _x ) and s _k (H ₂ ) does not change. The same magnetism is maintained. On the other hand, in the vicinity of the domain wall 42, the magnetized Mg in different directions is added at each position (X i, Yj). Magnetized Mg rotates. Second and third test detection value s _k (H ^, the average value of s _k (H ₂₎ is increased or decreased according to the angle measured from a defined direction.

For example, as shown in [Equation 2], the second and the second values are calculated from twice the first detection value s _k (H ₀ ) (3) When the sum of the detected values s _k (1 ^) and s _k (H ₂ ) is subtracted, as shown in FIG. 5E, around the domain wall 42 42a, each position (X i Y j) The porcelain vector remains. First, second and third detection values _{_{s k (H.), s k}} (H), since it is assumed to include uniformly noise to s _k (H _2), Noi's based on the subtraction is Offset. Pure magnetization vectors are specified. On the other hand, in the region outside the movement range of the domain wall 42 42 a, the magnetized Mg is virtually canceled (Mg 0). In this way, only the domain walls 42a42 are highlighted. Therefore, a clear magnetic domain structure can be visualized regardless of the surface state of the magnetic body 14.

Moreover, as is clear from FIG. 5E, the direction of the magnetization Mg is distinguished between the magnetic domains 41 a 41 b 41 across the domain wall 42 42 a. If the direction of the magnetized Mg is visually recognized, the direction of the magnetized Mg in the magnetic domains 41 a 41 b 41 can be relatively easily specified. For example, as shown in FIG. 5F, even when only the in-plane magnetization X component is detected, according to a calculation process such as [Equation 2], the direction of the magnetization Mg in the magnetic domains 41 a 41 b 41 is Can be fully inferred. As in [Equation 2], it is not always necessary to calculate the average value from the N measurement results in calculating the output value t (H ₀ ). In other words, N = l may be set in calculating the output value t (H.). In addition, any calculation process may be executed as long as it is based on the above principle.

Here, as shown in FIG. 6A, it is assumed that a counterclockwise return magnetic domain is established by the magnetic body 14 in place of the above-described turnaround magnetic domain. Magnetic field strength H. When the magnetic field 19 acts on the magnetic body 14 with a smaller magnetic field strength, as shown in FIG. 6B, in the magnetic body 14, the magnetic domain 41a expands as the magnetic field 19 decreases. Domain 41b shrinks. The movement of the domain wall 42 a 42 is caused. At this time, the domain walls 41a and 42 move in the direction opposite to the clockwise return magnetic domain described above (see FIG. 5B). Conversely, magnetic field strength H. When a magnetic field 19 is applied to the magnetic body 14 in a large magnetic field strength H ₂ than, as shown in FIG. 6 C, the magnetic domain 41 b with the increase of the magnetic body 14 in the magnetic field 19 that to expand. Domain 41a shrinks. The movement of the domain wall 42 a 42 is caused. The domain wall 42a42 moves in the opposite direction to the clockwise return magnetic domain described above.

As before, the second detection value s _k (Η _χ), and the third detection value s _k (H ₂₎ is of the addition Then, as shown in FIG. 6D, for example, in the moving range of the domain wall 42a, the magnetic direction vectors different from each other at the respective positions (X i, Yj) are added. In particular, in the moving range of the domain wall 42 42a, the antiparallel magnetizations are virtually canceled at each position (X i, Yj) (Mg = 0). In the region outside the moving range of the domain walls 42 and 42a, the magnetization vectors of the same direction are added for each position (Xi, Yj). For example, as shown in [Equation 2], the sum of the second and third detection values s _k (H _x ) and s _k (H ₂ ) is subtracted from the double value of the first detection value s _k (H ₀ ). Then, as shown in Fig. 6E, the magnetization vector remains at each position (Xi, Yj) around the domain walls 42 and 42a. As is clear from the comparison with FIG. 5E, in the output value t (H ₀ ), the magnetization can be specified in the opposite direction to the clockwise return magnetic domain. For example, as shown in FIG. 6F, according to the calculation processing of [Equation 2], even when only the in-plane magnetization X component is detected, the direction of the magnetization Mg in the magnetic domains 41 a and 41 b 41 is as follows. It can be fully inferred. The clockwise return domain and the counterclockwise return domain can be reliably distinguished.

In the Kerr microscope 11 as described above, it is desired that saturation of the magnetization be avoided when observing the magnetic body 14. When the magnetization is saturated in the magnetic body 14, the structure of the magnetic domain before that is completely destroyed. It is expected that the connection relationship between the domain walls 42a and 42 will change. The first magnetic field strength may be set to a value sufficiently larger than the magnetic field strength that induces the saturation of the magnetization. The second magnetic field strength H ₂ may be set to a value sufficiently smaller than the magnetic field strength that induces the saturation of the magnetic field. Thus it is set first magnetic field strength and the second magnetic field strength H ₂ is connected relation of a domain wall between which is established a magnetic body 14 is expected to be reliably maintained. However, the first magnetic field strength 1 ^ must be set to a magnitude that produces a difference between the first detected value s _k (H ₀ ) and the second detected value s _k (Hi). Similarly, the second magnetic field strength H ₂ must be set to a magnitude that produces a difference between the first detected value s _k (H.) and the third detected value s _k (H ₂ ).

Generally, the magnetic material 14 has the first and second magnetic field strengths based on the inherent properties.

The magnitude of H _{2 and} the amount of movement of the ί 兹 walls 42 a and 42 are correlated. Therefore, in the force-microscope 11, the first magnetic field strength 1 ^ and the The size of the 2 magnetic field intensity H ₂ is desirable to be able to change. The user may be adjusted first magnetic field strength H丄and size of the second magnetic field strength H ₂ based on the image of the magnetic domain to be displayed on the screen of the display device 33.

The inventor has verified a comparative example. In this comparative example, as shown for example in FIG. 7 A to FIG 7 C, the magnetic field strength specified in the same manner as described above H _Q, the magnetic field in the first magnetic field strength H _t and the second magnetic field intensity H ₂ is the magnetic body 14 Is applied. However, in this comparative example, the second detection value s _k (H _x ) is subtracted from the third detection value sk _k ₂ ) when detecting the domain walls 42 a and 42. In this case, as shown in FIG. 7D, the detected value of the magnetized Mg is canceled in the magnetic domains 41a, 41b, and 42. The domain walls 42a and 42 can be clearly drawn.

On the other hand, as shown in FIGS. 8A to 8C, in this comparative example, a situation where a counterclockwise return magnetic domain is established by the magnetic body 14 instead of the clockwise return magnetic domain will be verified. In this comparative example, when the second detection value s _k (H _x ) is subtracted from the third detection value s _k (H ₂ ) in detecting the domain walls 42 a and 42, as shown in FIG. 42a, 42 can be clearly depicted. However, as is apparent from the comparison between FIG. 7E and FIG. 8E, the direction of the magnetic field cannot be distinguished at all based on the in-plane magnetization X component. As is clear from the comparison between FIG. 7F and FIG. 8F, the direction of magnetization cannot be distinguished at all based on the in-plane magnetization y component. As described above, in the comparative example, the domain walls 42a and 42 are specified, but the direction of the magnetic domain in the magnetic domains 41a, 41b and 41 cannot be specified at all.

In the force microscope 11 according to the first embodiment described above, for example, as shown in FIG. 9, another processing operation may be used in observing the magnetic domain. The CPU 31 implements a processing operation according to a predetermined software program. When the observation is started, the CPU 31 performs initialization in step T1. In step T2, a magnetic field is applied to the magnetic body 14 at an initial magnetic field strength 1 ^ based on the processing operation of the CPU 31. When applying a magnetic field, the CPU 31 generates a predetermined command signal. The electromagnet driver 18 supplies current to the electromagnets 17 and 17 based on such command signals.

The initial magnetic field strength H is the designated magnetic field strength H. The magnetic field strength is set to be smaller than that. As before, if any magnetic field strength H _k is set to a negative value (H _k <0), The direction of 19 is reversed. As the negative value decreases, the field after reversal increases. The magnetic field strength H _k can include a “0 (zero)” value. For example, the specified magnetic field strength H. If is set to “0”, the initial magnetic field strength is set to a negative value. In step .tau.3 CPU 31 is you get position (X i, Y j) of the detected value s (H _k). The detection value s (H _k ) is specified from the detection signal output from the AZD converter 28 as described above. The CPU 31 records the detected value s (H _k ) in the storage device 32, for example.

In step T4, the CPU 31 resets the magnetic field strength H _k . Magnetic field strength Hi _nc increment the previous field strength H _k are summed. At step T5, the CPU 31 updates the algebra k. In the subsequent step _T6 , a magnetic field 19 is applied to the magnetic body 14 at a magnetic field strength Hk based on the processing operation of the CPU 31. That is, the magnetic field strength H _k of the magnetic field 19 increases. CPU 31 in step T 7 acquires position (X i, Y j) of the detected value s (H _k).

Step T 8, CPU 31 calculates the output value t of the magnetic field strength H _{_k} (H _k).

The CPU 31 calculates an output value t (H _k ) based on, for example, the odd function f (H) and the even function g (s) according to the following equation.

[Formula 4]

… (

However,

[Formula 5]

H = H _k -H ₀ ... (5)

...) The principle of calculation will be described later. The calculated output values t (H _k ) are accumulated in step T9. In step T 10, the magnetic field strength H _k is whether the host vehicle has reached the maximum magnetic field strength Eta _New is determined. If not, the processing operation of the CPU 31 returns to step # 4 again. As the magnetic field strength increases, the output value t (H _k ) is obtained at each magnetic field strength H _k . Here, the maximum magnetic field strength H _N is the specified magnetic field strength H. It is set to a larger magnetic field strength. In this case, the initial magnetic field strength 1 ^ Degree H. The range up to the magnetic field strength H. This corresponds to a smaller first magnetic field strength range. On the other hand, the specified magnetic field strength H. The range from to the maximum magnetic field strength H _N is the magnetic field strength H. This corresponds to a larger second magnetic field strength range.

As a result of accumulating the output values t (H _k ) obtained at the individual magnetic field strengths H _k , the output values t (H.) are specified. The output value t (H.) specifies whether the magnetization caused by the increase in the magnetic field 19 is increased or not. The prescribed magnetic field strength H depends on the presence or absence of such an increase. In the magnetic body 14 exposed to the magnetic field, the position of the domain wall can be specified. Moreover, the direction of magnetization in the magnetic domain can be estimated relatively easily. For example, if an increase in magnetization is detected during a change in the first magnetic field strength range, the output value t (H ₀ ) will be greater than the “0 (zero)” value. At this time, in the magnetization vector at the position (X i, Y j), for example, the magnetization component can be specified in the specified direction (X axis) in the positive direction. On the other hand, if an increase in the magnetic field is detected during a change in the second magnetic field strength range, the output value t (H.) indicates a value smaller than the “0 (zero)” value. At this time, in the magnetization vector, the magnetization component can be specified in the opposite direction, that is, in the negative direction of the X axis.

When the completion of the calculation of the output value t (H.) is confirmed in step T10, the CPU 31 performs a display process based on the output value t (H.) in step T11. The magnetization measured at the position (Xi, Yj) is thus visualized. Thereafter, pixels are determined at all positions (Xi, Yj) of the matrix LXM. Thus, the domain walls 42 a and 42 are drawn on the screen of the display device 33.

Based on the above-described steps T2 to T10, the following calculation processing is realized.

[Equation 6]

Q) =-[f (H) 'g (s)] ... (7)

Here, the principle of [Equation 6] will be briefly described. Designated magnetic field strength H, as shown in Figure 1 OA. When the magnetic field 19 acts on the magnetic body 14 in the magnetic field 14, magnetic domains 41a, 41b, and 41 are established in the magnetic body 14. Next, when the magnetic field 19 acts on the magnetic body 14 with the initial magnetic field strength Hi, as shown in FIG. 10B, in the magnetic body 14, the magnetic domains 41b are enlarged as the magnetic field 19 decreases. Domain 41a shrinks. The movement of the domain walls 42a and 42 is caused. Conversely, magnetic field strength H. Magnetic field strength greater than H _N When the field 19 acts on the magnetic material 14, as shown in FIG. 10C, the magnetic domain 41 a of the magnetic material 14 expands as the magnetic field 19 increases. Domain 4 1 b shrinks. The movement of the domain walls 42a, 42 is caused. Therefore, as the magnetic field strength H _k increases from the initial magnetic field strength to the maximum magnetic field strength H _N , the domain wall 42 a crosses the predetermined measurement points 43 a and 43 b. Thus, when the domain wall 42 a crosses, the magnetization Mg changes at the individual measurement points 43 a and 43 b. That is, the magnetization M g rotates.

At this time, at the measuring point 43a, the magnetic field strength is H from the initial magnetic field strength. The magnetization rotates before reaching. That is, the specified magnetic field strength H. The magnetization rotates in the first magnetic field strength range smaller than that. With the rotation of the magnetization, as shown in FIG. 11A, at the measurement point 43a, the magnetic field Mg increases rapidly. According to [Equation 6] described above, as is apparent from FIG. 12A, the difference s in the detected value shows a predetermined value during the rotation of the magnetization, but “0 ( Zero) "value is maintained. Here, the difference s in the detected values corresponds to a change in the magnetization, that is, a differential value of the increase.

On the other hand, at the measurement point 4 3 b, the magnetic field strength H. The magnetization rotates from to the maximum magnetic field strength H _N. That is, the specified magnetic field strength H. The magnetization rotates in the second magnetic field strength range larger than. With the rotation of the magnetization, the magnetization Mg increases rapidly at the measurement point 43 b as shown in FIG. 11B. According to [Equation 6] above, as apparent from Fig. 12B force, the difference s in the detected value shows a predetermined value at the time of the rotation of the magnetization, but before the rotation of the magnetization or after the rotation of the magnetization. The “0 (zero)” value is maintained.

When the even function g (s) is multiplied by the odd function f (H), the difference s is multiplied by a negative value at the measurement point 43a, as is clear from Fig. 12A. On the other hand, as shown in FIG. 12B, at the measurement point 43 b, the difference s is multiplied by a positive value. Therefore, measurement point 43a and measurement point 43b can be reliably distinguished. That is, the specified magnetic field strength H. In the magnetic body 14 exposed to the above magnetic field, the directions of the magnetic domains in the magnetic domains 41a and 41b are surely distinguished. Moreover, as long as the same position (X i, Y j) is maintained, it is assumed that the detected value s (H _k ) contains noise evenly, so that the influence of noise on detection is reliably eliminated. Can be

For (H), for example, a step function such as the following equation may be used. [Formula 7] ΛΗ) ~ (8)

In addition, an odd function f (H) such as

[Equation 8]

f HH ((9) According to such an odd function f (H), at the output value t (H ₀ ), the magnetic field strength H _{k at} which the rotation of the magnetization is caused and the specified magnetic field strength H. The value proportional to the difference from can be specified. It can be seen that the structure of the magnetic domains 41a, 41b can be observed in more detail.

On the other hand, the following function may be used for the even function g (s). According to these even functions, the sensitivity to the change in magnetization can be increased.

[Equation 9]

(= | "(η> 1) ... (10)

In addition, a step function such as the following equation may be used for the even function g (s). Here, the threshold s _TH may be appropriately set based on the magnitude of noise or the like.

[Formula 10]

As described above, the initial magnetic field intensity may be set to a value sufficiently larger than the magnetic field intensity that induces the saturation of the magnetization. The maximum magnetic field strength H _N may be set to a value sufficiently smaller than the magnetic field strength that induces magnetization saturation. If the initial magnetic field strength and the maximum magnetic field strength H _N are set in this way, it is expected that the connection relationship between the domain walls established in the magnetic body 14 will be maintained. However, the initial magnetic field strength and the maximum magnetic field strength H _N are large enough to determine the increase in magnetization based on the output value t (H ₀ ). Must be set. According to the above principle, the direction of the magnetic field cannot be detected in the magnetic domains 41a, 41b, 41 unless the movement of the domain walls 42a, 42 is generated. Moreover, in the same manner as described above, the force one microscope 1 1, the size of the easy initial magnetic field strength on the basis of the ratio comparatively to the operation of the user and the maximum magnetic field intensity H _N is desirable to be able to change. The user may adjust the magnitude of the initial magnetic field strength and the maximum magnetic field strength H _N based on the image of the magnetic domain displayed on the screen of the display device 33.

In the processing operation shown in FIG. 9, the presence or absence of the decrease in magnetization caused by the decrease in the magnetic field strength may be specified by the output value t (H ₀ ). In this case, it may be set large maximum magnetic field strength than the magnetic field strength H _G specified in the initial magnetic field strength. The magnetic field strength H _k is the specified magnetic field strength H from this initial magnetic field strength. It is only necessary to reduce the minimum magnetic field strength H _N to a smaller value. Here, the range H from the initial magnetic field strength to the magnetic field strength H ₀ corresponds to the second magnetic field strength range. Magnetic field strength H. The range from to the minimum magnetic field strength H _N corresponds to the first magnetic field strength range.

As shown in Fig. 13A, the magnetic field strength H at the measurement point 43a. The magnetization rotates from to the minimum magnetic field strength H _N. With the rotation of the magnetization, the magnetization Mg sharply decreases at the measurement point 43 b. According to [Equation 6] described above, as apparent from FIG. 14A, the difference s in the detected values shows a predetermined value when the magnetization is rotated, but before the rotation of the magnetization or after the rotation of the magnetization, “0 ( Zero) "value is maintained. On the other hand, at the measurement point 43 b, the initial magnetic field strength changes to the magnetic field strength H. The magnetization rotates before reaching. As shown in Fig. 13B, the magnetization Mg decreases rapidly with the rotation of the magnetization. According to [Equation 6] described above, as apparent from FIG. 14B, the difference s in the detected value shows a predetermined value during rotation of the magnetization, but “0 ( Zero) "value is maintained. Thus, similarly to the above, the measuring point 43a and the measuring point 43b can be reliably distinguished. Here, the difference s in the detected values corresponds to the differential value of the change, that is, the decrease of the magnetization.

Also in this case, as described above, the initial magnetic field strength may be set to a value sufficiently smaller than the magnetic field strength that induces the saturation of the magnetization. The minimum magnetic field strength H _N may be set to a value sufficiently larger than the magnetic field strength that induces the saturation of the magnetic field. This is the first time If the initial magnetic field strength and the minimum magnetic field strength H _N are set, it is expected that the connection relationship between the domain walls established in the magnetic body 14 will be maintained. However, the initial magnetic field strength and the minimum magnetic field strength H _N must be set to such a value that the increase in magnetization can be determined based on the output value t (H ₀ ). As before, the size of the relatively simple initial magnetic field strength and the minimum magnetic field intensity H _N based on the user's operation is desired that as possible out to be changed.

Furthermore, in the above-described processing operation, the following expression may be used instead of [Equation 6] in calculating the output value t (H.). In the following equation, an arbitrary odd function h (s) is used instead of the even function g (s) described above.

[Formula 1 1]

^ o) = -∑ [RH) · h {s) · sgn O] · '. (12)

[Formula 12]

H = H _k -H ₀ …)

~ (6)

T = H _k -H _k _ _x- .. (13)

Here, s gn (T) indicates the sign of Τ as in the following equation.

[Equation 13]

"1 <> 0)

s ^{gn (r)} = li ₍ r <o ⁾

If Τ = 0, s gn (T) may be either a “0” value, a “1” value, or a “−1” value.

According to the adoption of such an odd function h (s), as shown in FIG. 15A, even when the magnetic field 19 increases or when the magnetic field 19 decreases, when the domain wall 42a crosses, The product of the odd functions h (s) and s gn (T) at each measurement point 43a shows a positive value. Similarly, as shown in FIG. 15B, even when the magnetic field 19 increases, and conversely, when the magnetic field 19 decreases, the odd function 1Ί (s) at each measurement point 43 b when the domain wall 42 a crosses. The product of and s gn (T) is positive. Otherwise, the difference The noise can be mutually canceled based on the sign (10,-) of the noise included in the minute s. For the odd function h (s), for example, a function such as the following equation may be used _c [Equation 14]

In addition, a step function such as the following equation may be used for the odd function h (s). The threshold value s _TH may be set appropriately.

[Equation 15]

FIG. 16 schematically shows the structure of a force microscope according to the second embodiment of the present invention. A waveform generator 45 is incorporated in the Kerr microscope 11a. The waveform generator 45 generates, for example, a first waveform signal such as a cosine wave of a first frequency and a second waveform signal likewise a cosine wave of a second frequency. The second frequency is set to, for example, twice the frequency of the first frequency. The phase difference between the first waveform signal and the second waveform signal is set to “0 (zero)” value. That is, the phases of the two coincide. The first waveform signal is supplied to the electromagnetic stone driver 18. The electromagnet driver 18 can generate a magnetic field that changes based on the first waveform signal. The magnetic body 14 is exposed to a magnetic field that changes at a specific cycle based on the first waveform signal.

A multiplier 46 is connected to the differential amplifier 27. The multiplier 46 multiplies the electric signal output from the differential amplifier 27, that is, the detection signal, by the second waveform signal supplied from the waveform generator 45. Thus, the multiplier 46 calculates the product of the detection value specified by the detection signal and the numerical value specified by the second waveform signal.

The low-pass filter 47 is connected to the multiplier 46. In the low-pass filter 47, the output of the multiplier 46 is subjected to integration processing. The output of the low-pass filter 47 is converted to a digital signal by the AZD converter 28. These digital signals are taken into the CPU 31 of the computer 29. In the figure, configurations and structures equivalent to those of the above-described first embodiment are denoted by the same reference numerals. According to the Kerr microscope 11a, the rotation of the magnetization can be specified by the detection signal in accordance with the change of the magnetic field 19 acting on the magnetic body 14. In the product of the detected value and the numerical value, the rotation of the magnetization can be emphasized. Moreover, in this emphasis, different polarities (signs) can be specified in the detection signal according to the direction of the magnetization. In this way, the position of the domain walls 42 a and 42 can be projected on the screen of the display device 33 of the Kerr microscope 11 a. The directions of magnetization in the magnetic domains 41a, 41b, 41 can be specified relatively easily.

Here, the principle of the force microscope 11a according to the second embodiment will be briefly described. For example, assume that measurement points 43a and 43b are set on the magnetic body 14 of the counterclockwise return magnetic domain as shown in FIGS. 6A and 8A. When the magnetic field 19 is generated based on the first waveform signal, the magnetic field 19 repeats increasing and decreasing at a specific cycle. At this time, as shown in FIG. 1A, for example, at the measurement point 43 b, the magnetization changes as the magnetic field 19 increases or decreases. The magnetization repeats reversal according to the increase and decrease of the magnetic field 19. As shown in FIG. 17B, the magnetization repeats in the same manner at the measurement point 43 a according to the increase and decrease of the magnetic field 19. In this case, the magnetization M (t) can be expressed by the following step function.

[Equation 16]

M Mg (u <t <v) 'hi7)

Here, u and V values of the measuring points 4 3 b can be expressed by the following equation _t

[Equation 17])

Similarly, the u value and V value of the measurement point 4 3a can be expressed by the following equations. [Equation 18] τ

Τ

^V 2 = ^ ⁺ (° 2 ^{+ d} l) '' (21)

However, cee. ₂ is regarded as a parameter related to the position from domain wall 42 a <(! ゃゃゃ It is considered a parameter related to the delay of movement of domain wall ^ 2 a. In particular. Measurement point 43 b and measurement point When 43a is arranged symmetrically with respect to the domain wall 42a and is close to each other, the following equation is approximately established.

[Equation 19]

c− θ = c 22

d = d _l -d ₀ -"(23)

M (t) can be Fourier series expanded based on the following equation.

[Equation 20]) + • (24)

As a result, the following equation is obtained.

[Equation 21] 1 cos [iy (c + d)] + cosmic-<i)]

^ (1) = ^ ― ^ -2Mg '

π α _{ (2) = — (-c + me) _{+ C0S} [c-me]… () [w {c ₊ d)]-^ cd} _2Mg …)

π sin [iw (-c + d)]-sin [w (-c-d)]

(2) = 2Mg to (28) π (l) ^ ^sin [ ² ( ^c + me) + sin [2 ^ (c first) _Mg ( ₂₉ )

π a ₂ (2) ₌ — sin [2w (-c + me] _{+ S} in [2 (-c-me)… (^

π 2h) _ one cos [2w (c first) + cos [2 + me] _Λ .., ( ₃

π b ₂ (2) =-c. s [2-me] _{+ C.} s [2 -c ₊ me] _Mg …) π

Here, & E (1), b, (1 ), a 2 (1) and b ₂ (1) shows the coefficients obtained at the measurement point 43 b. (2), b, (2), a ₂ (2) and b ₂ (2) indicate the coefficients obtained at the measurement point 43a. Therefore, as is apparent from the following equation, when the frequency of the first waveform signal and the frequency of the second waveform signal are equal, the measurement point 43b and the measurement point 43a cannot be distinguished by the detection signal. The polarity (sign) of measurement point 43b and measurement point 43a match.

[Equation 22]

^ (1) = ¾ (2) '·' (33)

¾ (1) = ¾ (2)-(34)

On the other hand, if the frequency of the second waveform signal is set to be twice the frequency of the first waveform signal, the measurement point 43b and the measurement point 43a can be completely distinguished. 18A and 18B, the signal polarity is different between the measurement point 43b and the measurement point 43a. The direction of the magnetization in the magnetic domains 41a, 41b, 41 as well as the position of the domain wall 42a can be specified.

[Equation 23]

2 (1) = -¾ (2)

¾ (1) =-¾ (2) ー (36) However, as is clear from the following equation, the power of the double frequency component coincides at the measurement point 43 b and the measurement point 43 a. Therefore, even if the double frequency component force s is detected by the spectrum analyzer, the direction of magnetization in the magnetic domains 41 a, 41 b, and 41 cannot be specified.

[Equation 24]

" ₂ (1) ² + ¾ (1) ^2- " ₂ (2) ² + ¾ (2) ² 〜 (37)

If the movement delay of the domain wall 42 a is small, d == 0 may be set. As a result, for example, according to Fourier series expansion, the following equation is obtained.

[Equation 25]

, sm (2ct c _ _{Λ / Γ} .,

~ 2Mg ~ (38)

π

, ヽ sm (2a) c) _ _{Λ / Γ} ,

α ₂ (2) = — ^ ^J -2Mg

π

¾ (1) = ¾ (2) = 0… ()

Therefore, if a component whose peak phase coincides with the second waveform signal is detected in the detected value, the magnetic domains 41a and 41b can be favorably obtained even if the movement delay of the domain wall 42a is small. The orientation of the magnetization within 41 can be specified.

In addition, the phase difference between the first and second waveform signals may be set to, for example, 180 ° or 180 °. A triangular wave may be used instead of a cosine wave or another trigonometric wave. The combination of the multiplier 46 and the low-pass filter 47 may be replaced by a so-called suck-in amplifier. Further, the functions of the multiplier 46 and the low-pass filter 47, that is, the function of the integrator, may be realized by, for example, a software program. Such a processing operation of the software program may be performed on the output of the differential amplifier 27, for example. At this time, the output of the differential amplifier 27 may be converted to a digital signal by, for example, an analog digital (AZD) converter and then transferred to the software program.

FIG. 19 schematically shows the structure of a Kerr microscope according to the third embodiment of the present invention. In this force microscope 11b, a high-pass filter is provided between the differential amplifier 27 and the multiplier 46. Evening 48 is arranged. In this high-pass filter 48, a differential process is performed on the detection value output from the differential amplifier 27. Therefore, the detected value after the differentiation processing is input to the multiplier 46. In addition, configurations and structures equivalent to those of the above-described second embodiment are denoted by the same reference numerals.

In this force microscope 1 lb, the waveform generator 45 sets the phase difference between the first waveform signal and the second waveform signal to + 90 ° or −90 °. That is, when, for example, a cosine wave of the first frequency is used for the first waveform signal, a sine wave of the second frequency may be used for the second waveform signal. As before, the second frequency is set to twice the frequency of the first frequency.

According to such a Kerr microscope 11b, the rotation of the magnetization can be specified by the detection signal according to the change in the magnetic field 19 acting on the magnetic body 14. In the product of the detected value and the detected value after the differentiation processing, the rotation of the magnetic field can be emphasized. In addition, different polarities (signs) can be specified in the detection signal according to the direction of the magnetization in this emphasis. Thus, the force microscope 11 a can project the positions of the domain walls 42 a and 42 on the screen of the display device 33. The direction of magnetization in the magnetic domains 41a, 41b, 41 can be specified relatively easily.

Assume that measurement points 43a and 43b are set on the magnetic body 14 of the counterclockwise return magnetic domain as shown in FIGS. 6A and 8A. When the magnetic field 19 is generated based on the first waveform signal, the magnetic field 19 repeats increasing and decreasing at a specific cycle. At this time, as shown in FIG. 17A, for example, at the measurement point 43 b, the magnetic field changes as the magnetic field 19 increases or decreases. The magnet repeats its rotation as the magnetic field 19 increases or decreases. As shown in FIG. 17B, at the measurement point 43 a, the magnetic field repeats the rotation in accordance with the increase and decrease of the magnetic field 19.

As is clear from FIG. 2 OA and FIG. 20B, when the frequency of the first waveform signal and the frequency of the second waveform signal match, the measured signal points 4 3b and 4 3a It cannot be distinguished. The polarity (sign) of measurement point 4 3b and measurement point 4 3a match. On the other hand, when the frequency of the second waveform signal is set to be twice as high as that of the first waveform signal, as shown in FIGS. 21A and 21B, the measurement points 4 3b and 4 The signal polarity differs between 3a and 3a. Measurement point 4 3b and measurement point 4 3a can be completely distinguished. As a result, the domain 4 1 a, 4 1 Information on the direction of the magnetic sill in b, 41 can be obtained.

In the Kerr microscope 11, lla, and lib as described above, a detection signal may be generated based on a so-called CCD. As the light source 21, a pulsed light source that emits light intermittently may be used. In addition, the above-described magnetic field generating mechanism 16 may include a plurality of sets of electromagnets 17 that generate magnetic fields 19, 19 along a plurality of directions. According to such a magnetic field generation mechanism 16, the in-plane magnetization X component and the in-plane magnetization Y component can be detected from various directions. 'The movable stage 12 may rotate around a rotation axis orthogonal to a horizontal plane.

Claims

The scope of the claims

1. The magnetic field strength H specified for the magnetic material along the predetermined direction. Applying a magnetic field in the step of: detecting the magnetization of the magnetic material based on the magneto-optical effect, and specifying a first detected value of the magnetization; First magnetic field strength H! A step of detecting the magnetization of the magnetic material in the magnetic field and specifying a second detection value of the magnetization; A step of detecting a magnetic I inhibit the magnetic substance, to identify a third detection value of the magnetization in a magnetic field Do of the second magnetic field strength H ₂ larger than, 2: _ 1: - first based on 1 weighting, Adding the second and third detection values.

2. In the magnetization observation method according to claim 2, in addition of the first, second, and third detection values, an output value t, a first detection value s (H _Q ), and a second detection value s

(Η,) and the third detection value s (Η ₂ )

[Equation 26]

_{_{0) = 2 0) - +}} ^ ¾)] ... ( magnetization observed method characterized by 1) is satisfied.

3. The magnetization observation method according to claim 1 or 2, wherein the first magnetic field strength is set to a magnitude that maintains a connection relationship between domain walls established in a magnetic body. Characterized magnetization observation method.

4. The magnetic field observation method according to any one of claims 1 to 3, wherein the second magnetic field strength is set to a magnitude that maintains a connection relationship between domain walls established in a magnetic body. A magnetization observation method characterized by being performed.

5. The magnetic field observation method according to any one of claims 1 to 4, wherein the first magnetic field strength is a magnitude that produces a difference between a first detection value and a second detection value. A magnetization observation method characterized by being set as follows.

6. The magnetic field observation method according to any one of claims 1 to 5, wherein the second magnetic field strength is a magnitude that produces a difference between the first detection value and the third detection value. A magnetization observation method characterized by being set as follows.

7. A magnetic field generating mechanism that generates a magnetic field with a specified magnetic field strength, a first magnetic field strength smaller than the specified magnetic field strength, and a second magnetic field strength larger than the specified magnetic field strength, and a magnetic field generating mechanism. An optical system that guides light to a magnetic body exposed to a magnetic field, and corresponding first, second, and third magnetic fields based on the magneto-optical effect of the magnetic body when a magnetic field having a specified magnetic field strength and first and second magnetic field strengths is applied. A photodetector that outputs a detection signal that specifies a third detection value, and a processor that is connected to the photodetector and that adds the first, second, and third detection values based on a weighting of 2: —1 :: 1. And a magnetization observation device.

8 · Specified magnetic field strength H. Obtaining a first detection signal generated based on the magnetization of the magnetic substance disposed in the magnetic field of the specified magnetic field strength. Process and designation of the magnetic field strength H 0 field of the larger second magnetic field strength H ₂ than to obtain a second detection signal generated based on the magnetization of the magnetic body arranged in the magnetic field of the small first magnetic field strength than Obtaining a third detection signal generated based on the magnetization of the magnetic substance disposed in the first and second detection signals based on the weighting of 2: 1-1: 11, respectively. And a step of adding a detected value of magnetization to be performed by a processor.

9. A step of causing the magnetic body to apply a magnetic field that changes in a first magnetic field strength range smaller than a specified magnetic field strength, and a step of changing the magnetization based on the magneto-optical effect of the magnetic body during a change in the magnetic field within the first magnetic field strength range. Detecting the presence or absence of a change; applying a magnetic field that changes in a second magnetic field strength range greater than a specified magnetic field strength to the magnetic body; Detecting the presence or absence of a change in magnetization based on the magneto-optical effect of the body.

10. The method for observing magnetization according to claim 9, wherein the detection of the presence or absence of a change is performed. Therefore, a magnetization observation method characterized by increasing the magnetic field strength in the first and second magnetic field strength ranges and detecting an increase in magnetization corresponding to a change in magnetization.

11. The magnetization observation method according to claim 10, wherein a differential value is specified based on a change in magnetization when detecting an increase in magnetization.

12. The magnetic field observation method according to claim 11, wherein the step of specifying the differential value includes increasing the magnetic field strength discretely in the first and second magnetic field strength ranges. The process of detecting the magnetization of the magnetic material based on the magneto-optical effect for each magnetic field strength and specifying the detected value of magnetization for each magnetic field strength, and subtracting the previous detected value from the current detected value to obtain the magnetization Calculating a change value.

13. In the magnetization observation method according to any one of claims 9 to 12, when detecting the presence or absence of a change, the magnetic field intensity is reduced in the first and second magnetic field intensity ranges, A magnetization observation method characterized by detecting a decrease in magnetization corresponding to a change.

14. The magnetization observation method according to claim 13, wherein a differential value is specified based on a change in magnetism in detecting the decrease in magnetization.

15. The magnetization observation method according to claim 14, wherein, in specifying the differential value, a step of discretely reducing the magnetic field strength in the first and second magnetic field strength ranges; Detecting the magnetization of the magnetic material based on the magneto-optical effect for each magnetic field strength, and identifying the detected value of magnetic field for each magnetic field strength, and subtracting the previous detected value from the current detected value to obtain the magnetization value. And a step of calculating a change value.

16. A magnetic field generating mechanism that generates a magnetic field that changes in the first magnetic field strength range smaller than the specified magnetic field strength and the second magnetic field strength range larger than the specified magnetic field strength, and a magnetic field generated by the magnetic field generating mechanism An optical system that guides light to a magnetic body exposed to light, a light-receiving element that receives light returning from the magnetic body, and a light-receiving element that is connected to the light-receiving element to change the first magnetic field strength range and the second magnetic field strength range And a processor that detects the presence or absence of a change in magnetization based on the magneto-optical effect of the magnetic material during the change in magnetization.

17. A step of acquiring a first detection signal generated based on the magnetization of a magnetic substance arranged in a magnetic field that changes in a first magnetic field strength range smaller than a specified magnetic field strength, and magnetizing based on the first detection signal Detecting the presence or absence of a change in the magnetic field intensity; and obtaining a second detection signal generated based on the magnetization of the magnetic substance disposed in the magnetic field that changes in a second magnetic field strength range larger than the specified magnetic field strength; Detecting the presence or absence of a change in magnetization based on a second detection signal by a processor.

'18. A step of applying a magnetic field that changes at a specific cycle to the magnetic material based on the waveform signal, a step of detecting the magnetization of the magnetic material based on the magneto-optical effect, and specifying the detected value of the magnetization, Multiplying the detected value by a numerical value that periodically changes at twice the frequency of the waveform signal while synchronizing with the waveform signal in a fixed phase relationship. .

19. The magnetization observation method according to claim 18, further comprising a step of performing an integration process on a result of multiplication of the detected value and the numerical value. 20. The magnetic observation method according to claim 18 or claim 19, wherein the phase indicating the maximum value and the minimum value of the waveform signal is any one of the maximum value and the minimum value of the numerical value. A magnetization observation method characterized by the following:

21. The method for observing magnetization according to claim 18 or claim 19, wherein Prior to multiplication with a numerical value, a magnetization observation method further comprising a step of performing a differentiation process on the detected value.

22. The magnetization observation method according to claim 21, wherein the phase of the waveform signal indicating a local maximum value and a local minimum value matches the phase of the numerical value indicating an intermediate value between the local maximum value and the local minimum value. A method for observing magnetization, characterized in that:

2 3. A magnetic field generation mechanism that generates a magnetic field that changes at a specific cycle based on the waveform signal, an optical system that guides light to a magnetic body exposed to the magnetic field generated by the magnetic field generation mechanism, and feedback from the magnetic body A light-receiving element that outputs a detection signal that specifies the detection value of the magneto-optical effect based on the light that is emitted, and a period that is connected to the light-receiving element and synchronizes with the waveform signal with a fixed phase relationship at twice the frequency of the waveform signal A magnetization observation device, comprising: a multiplier for multiplying the detection signal by a periodically changing periodic signal. 24. The magnetization observation device according to claim 23, wherein a mouth-pass filter is connected to the multiplier.

25. The magnetization observation device according to claim 23, wherein a high-pass filter is disposed between the multiplier and the light receiving element.