Magnetization measurement method

Abstract

Achieved is a magnetization measurement method that enables measurement of the internal magnetization of a magnetic body. A magnetization measurement method (M) includes: converting step (M4, M10) for converting, into linearly polarized components having different polarization directions, each circularly polarized component (XR, XL) contained in a characteristic X beam Xc which is of characteristic X beams (Xc) emitted by the sample (S) and the direction of travel of which when emitted by a sample (S) forms a 90° angle with the magnetization at the surface of the sample (S); and a specifying step (M13) for specifying the internal magnetization of the sample (S) on the basis of the intensity of linearly polarized components derived respectively from the circularly polarized components (XR, XL).

Description

Technical Field

[0001] The present invention relates to a magnetization measurement method for measuring the magnetization of a magnetic material.

Background Art

[0002] In the development of devices using magnetic materials such as permanent magnets, electromagnetic steel sheets, and magnetic recording media, it is important to measure the spatial distribution of magnetization. As a technique for measuring the spatial distribution of magnetization, for example, a magnetization measurement device (described as a "magnetic material observation device" in Patent Document 1) described in Patent Document 1 is known. When a magnetic material is irradiated with an excitation line, characteristic X-rays are generated. These characteristic X-rays include a right circularly polarized component and a left circularly polarized component, and the magnetization at the generation point of the characteristic X-rays can be obtained from the inversion ratio of their intensities. The magnetization measurement device described in Patent Document 1 measures magnetization using this principle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the magnetization measurement device described in Patent Document 1, the implementation of a method for measuring the magnetization inside the sample is not sufficient, and this point remains a problem.

[0005] One aspect of the present invention has been made in view of the above problems, and an object thereof is to realize a magnetization measurement method capable of measuring the magnetization inside a sample.

Means for Solving the Problems

[0006] The magnetization measurement method according to one aspect of the present invention includes a conversion step of converting each circular polarization component included in characteristic X-rays emitted from a sample, the traveling direction of which forms a 90° angle with the magnetization on the surface of the sample when exiting the sample, into linearly polarized components with different polarization directions, and a specifying step of specifying the magnetization inside the sample based on the intensities of the linearly polarized components derived from each circular polarization component obtained in the conversion step.

Advantages of the Invention

[0007] According to one aspect of the present invention, a magnetization measurement method capable of measuring the magnetization inside a sample can be realized.

Brief Description of the Drawings

[0008]

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[0009] (Configuration of magnetization measuring device) The configuration of a magnetization measurement device 1 according to one embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing the configuration of the magnetization measurement device 1.

[0010] The magnetization measuring device 1 is a device for measuring the magnetization inside a sample S. The sample S is a magnetic body, for example, an electromagnetic steel sheet, whose surface has a magnetization direction substantially parallel to the surface. When the sample S is irradiated with an excitation ray P, characteristic X-rays X c It generates characteristic X-rays X c has a right-handed circularly polarized component X R and the left circularly polarized component X L The magnetization measuring device 1 includes a right-handed circularly polarized component X R Intensity I R and the left circularly polarized component X L Intensity I L Inversion ratio R = (I R -I L ) / (I R +I L ) from the characteristic X-rays X c The magnetization at the generation point of the excitation ray P is specified. The excitation ray P may be an electromagnetic wave beam or a charged particle beam. In this embodiment, an electromagnetic wave beam, more specifically an X-ray beam, and even more specifically a synchrotron radiation X-ray beam is used as the excitation ray P.

[0011] 1, the magnetization measurement device 1 includes a collimating optical element 11, a retarder 12, a double crystal spectrometer 13, a detector 14, and a control unit 15. The magnetization measurement device 1 may further include an excitation radiation source (not shown) that irradiates the sample S with an excitation radiation P.

[0012] Right-handed circularly polarized component X emitted from sample S R and left circularly polarized component X L Characteristic X-rays containing both c A collimating optical element 11 is disposed on the optical path of the X-rays. c The characteristic X-rays X that have passed through the collimating optical element 11 are c Hereinafter, this optical axis will also be referred to as a first light receiving axis L1. As the collimating optical element 11, for example, a collimating mirror such as a KB mirror (Kirkpatrick-Baez Mirror) or a Montel mirror, a collimating lens such as an X-ray lens, or a diffraction grating such as a Fresnel zone plate can be used. In this embodiment, a Montel mirror is used as the collimating optical element 11. The Montel mirror is advantageous in that it can achieve a large light receiving solid angle with a compact configuration.

[0013] The first light receiving axis L1 is set so that the angle it forms with the magnetization on the surface of the sample S is 90°. c is the characteristic X-ray X emitted from the sample S. c Among them, characteristic X-rays X form an angle of 90° with the surface of the sample S. c Here, the "angle between the traveling direction and the surface of the sample S" can be rephrased as "the angle between the traveling direction and the magnetization on the surface of the sample S." Note that the characteristic X-rays X c The angle between the surface of the sample S and the characteristic X-rays X is not required to be exactly 90°, but it is sufficient if the angle is 90° with integer precision, that is, 89.5° or more and 90.5° or less, as described later. c The angle between the surface of the sample S and the characteristic X-rays X c This can be rephrased as "the angle between the magnetization at the surface of sample S and the magnetic field."

[0014] A right-handed circularly polarized component X that has passed through the parallelizing optical element 11 R and left circularly polarized component X L Characteristic X-rays containing bothc On the optical path of c , a phase shifter 12 is arranged. The phase shifter 12 converts the two circularly polarized components X c included in the characteristic X-ray X parallelized by the parallelizing optical element 11 R , X L into two linearly polarized components X1 and X2 with different polarization directions. As the phase shifter 12, a crystal such as a single crystal of silicon, a single crystal of germanium, or a single crystal of diamond can be used. In the present embodiment, a single crystal of diamond is used as the phase shifter 12. The single crystal of diamond is superior to the single crystal of silicon and the single crystal of germanium in terms of high X-ray transmittance.

[0015] The phase shifter 12 is included in a plane perpendicular to the first light receiving axis L1 and is rotatable about a straight line that forms an angle of 45° with a plane including both the first light receiving axis L1 and the second light receiving axis L2 as the rotation axis. By rotating the phase shifter 12 by about 0.01°, it is possible to switch between performing the following conversion 1 and performing the following conversion 2. The first linearly polarized component X1 and the second linearly polarized component X2 are two linearly polarized components whose polarization directions are orthogonal to each other in a plane orthogonal to the optical axis of the characteristic X-ray X that has passed through the parallelizing optical element 11 c .

[0016] Conversion 1: Convert the right circularly polarized component X R into the first linearly polarized component X1 and convert the left circularly polarized component X L into the second linearly polarized component X2.

[0017] Conversion 2: Convert the right circularly polarized component X R into the second linearly polarized component X2 and convert the left circularly polarized component X L into the first linearly polarized component X1.

[0018] Note that the magnetization measuring device 1 may further include a phase shifter rotation mechanism (not shown) that rotates the phase shifter 12 as described above. Thereby, for example, the control unit 15 can automate the rotation of the phase shifter 12 by controlling the phase shifter rotation mechanism. Further, the phase shifter 12 may be configured to be rotatable about the first light receiving axis L1 as the rotation axis. In this case, by rotating the phase shifter 12 by 90°, it is possible to switch between performing the above-described conversion 1 and performing the above-described conversion 2.

[0019] Characteristic X-ray X including both the first linearly polarized component X1 and the second linearly polarized component X2 that have passed through the phase shifter 12 c On the optical path of ', a two-crystal spectrometer 13 is arranged. The two-crystal spectrometer 13 is for selectively reflecting a linearly polarized component having a specific polarization direction, a specific traveling direction, and a specific energy among the characteristic X-rays X c ' that have passed through the phase shifter 12. The two-crystal spectrometer 13 includes a first crystal 131 that selectively reflects a linearly polarized component having a specific polarization direction and a specific energy among the characteristic X-rays X c ' that have passed through the phase shifter 12, and a second crystal 132 that further reflects a linearly polarized component having a specific traveling direction among the linearly polarized components reflected by the first crystal 131. As the first crystal 131 and the second crystal 132, crystals such as a silicon single crystal, a germanium single crystal, and a diamond single crystal can be used. In the present embodiment, germanium single crystals are used as the first crystal 131 and the second crystal 132, and the 400 plane thereof is used as the reflection surface. Hereinafter, the optical axis of the characteristic X-ray X c ” reflected by the first crystal 131 is also referred to as the second light receiving axis L2. Further, the optical axis of the characteristic X-ray X c ” reflected by the second crystal 132 is also referred to as the third light receiving axis L3. The first light receiving axis L1, the second light receiving axis L2, and the third light receiving axis L3 are located on a common plane.

[0020] In this embodiment, the first crystal 131 is arranged to selectively reflect a first linearly polarized component X1 having a specific energy. Also, the second crystal 132 is arranged to selectively reflect a first linearly polarized component having a specific traveling direction. Therefore, when the phase shifter 12 performs the above conversion 1, the two-crystal spectrometer 13 selectively reflects a linearly polarized component having a specific energy and a specific traveling direction derived from the right circularly polarized component X R . On the other hand, when the phase shifter 12 performs the above conversion 2, the two-crystal spectrometer 13 selectively reflects a linearly circularly polarized component having a specific energy and a specific traveling direction derived from the left circularly polarized component X L .

[0021] The first crystal 131 is rotatable about an axis orthogonal to the plane including the light-receiving axes L1 to L3 as a rotation axis. Also, the second crystal 132 is rotatable about an axis parallel to the rotation axis of the first crystal 131 as a rotation axis. Also, the arrangement of the first crystal 131 and the second crystal 132 is a ++ arrangement or a -- arrangement, and when the space is divided into two half-spaces by a plane including both the rotation axis of the first crystal 131 and the rotation axis of the second crystal 132, the characteristic X-ray X c ' incident on the first crystal 131 of the two-crystal spectrometer 13 and the infinite point in the starting direction of the characteristic X-ray X c " emitted from the second crystal 132 of the two-crystal spectrometer 13 are included in the same half-space. As an example, when the same single crystal as the first crystal 131 is used as the second crystal 132 and the same crystal plane as the reflection surface of the first crystal 131 is used as the reflection surface of the second crystal 132, the orientations of the first crystal 131 and the second crystal 132 can be set so that θ1 = θ2 = 45°. In this case, the traveling direction of the characteristic X-ray X c ' incident on the two-crystal spectrometer 13 and the traveling direction of the characteristic X-ray X c " emitted from the two-crystal spectrometer 13 are opposite to each other. The functions realized by changing the arrangement of the first crystal 131 and the second crystal 132 will be described later with reference to different drawings.

[0022] Note that the magnetization measuring device 1 may further include a first crystal rotation mechanism that rotates the first crystal 131 about an axis orthogonal to the plane including the light receiving axes L1 to L3 as a rotation axis, and a second crystal rotation mechanism that rotates the second crystal 132 about an axis parallel to the rotation axis of the first crystal 131 as a rotation axis. Thereby, for example, by the control unit 15 controlling these crystal rotation mechanisms, the rotation of the first crystal 131 and the second crystal 132 can be automated.

[0023] Characteristic X-ray X including one of the first linearly polarized component X1 or the second linearly polarized component X2 reflected by the two-crystal spectrometer 13 c On the optical path of "", a detector 14 is arranged. The detector 14 is configured to detect the intensity of the characteristic X-ray X c " reflected by the second crystal 132 of the two-crystal spectrometer 13. As the detector 14, a semiconductor detector such as a germanium semiconductor detector or a silicon semiconductor detector can be used. In the present embodiment, as the detector 14, a silicon semiconductor detector, more specifically, a silicon drift detector is used. Note that as the detector 14, a two-dimensional detector in which semiconductor detectors are arranged in a matrix may be used. In this case, the characteristic X-ray X incident on the detector 14 c " can be adjusted according to the beam pattern.

[0024] In the present embodiment, the two-crystal spectrometer 13 is configured to selectively reflect the first linearly polarized component X1 having a specific energy. Therefore, when the phase shifter 12 performs the above conversion 1, the detector 14 mainly selectively detects a linearly polarized component derived from the right circularly polarized component X R and having a specific energy. On the other hand, when the phase shifter 12 performs the above conversion 2, the detector 14 mainly selectively detects a linearly circularly polarized component derived from the left circularly polarized component X L and having a specific energy.

[0025] The control unit 15 controls the phase shifter 12 to perform the above conversion 1, and then the intensity I of the characteristic X-ray X detected by the detector 14 c "+ Record it. As described above, when the phase shifter 12 performs the above conversion 1, mainly the characteristic X-ray X c The right circularly polarized component X contained in R The linearly polarized component derived from is incident. Therefore, the intensity I + Is the characteristic X-ray X c The right circularly polarized component X contained in R The intensity I of R Is approximately proportional to. Further, the control unit 15 controls the phase shifter 12 to perform the above conversion 2, and then records the intensity I of the characteristic X-ray detected by the detector 14 - Record it. As described above, when the phase shifter 12 performs the above conversion 2, mainly the characteristic X-ray X c The left circularly polarized component X contained in L The linearly polarized component derived from is incident. Therefore, the intensity I - Is the characteristic X-ray X c The left circularly polarized component X contained in L Is approximately proportional to the intensity of. Next, the control unit 15 calculates the inversion ratio R’=(I + And intensity I - From - I + - I - ) / (I + + I - ). This inversion ratio R’=(I + - I - ) / (I + + I - ) Is the characteristic X-ray X c The right circularly polarized component X contained in R The intensity I of R , And the characteristic X-ray X c The left circularly polarized component X contained in L The intensity I of L The inversion ratio R=(I R - I L ) / (I R + I L ) Calculated from is substantially the same. The sign of the inversion ratio R’ represents the direction of the projection of the magnetization at the generation point of the characteristic X-ray X c On the first light receiving axis L1. Also, the magnitude of the inversion ratio R’ is the characteristic X-ray X cIt has a value corresponding to the magnitude of the projection of the magnetization at the generation point onto the first light-receiving axis L1. The control unit 15 utilizes this principle to determine, from the inversion ratio R', the characteristic X-ray X c to identify the projection of the magnetization at the generation point onto the first light-receiving axis L1.

[0026] Note that the magnetization measurement device 1 can identify the spatial distribution of the magnetization in the sample S by repeating the above-described measurement while changing the generation point of the characteristic X-ray X c . For example, when the sample S is divided into a plurality of magnetic domains, a magnetic domain map of the sample S can be created using the magnetization measurement device 1.

[0027] In the present embodiment, a configuration is adopted in which two crystals 131 and 132 are interposed between the collimating optical element 11 and the detector 14. However, the present invention is not limited to this. That is, for example, the second crystal 132 may be omitted, and the detector 14 may be arranged on the optical path of the characteristic X-ray X c reflected by the first crystal.

[0028] Further, in the present embodiment, it is assumed that the angle formed by the magnetization on the surface of the magnetic body S and the first light-receiving axis is 90° in advance. However, the present invention is not limited to this. That is, the magnetization measurement device 1 is provided with a mechanism for tilting one or both of the optical system of the magnetization measurement device 1 and the sample S so that the angle formed by the magnetization on the surface of the magnetic body S and the first light-receiving axis is 90°. A configuration may be adopted in which the angle formed by the magnetization on the surface of the magnetic body S and the first light-receiving axis is made 90° using these mechanisms.

[0029] Also, when a collimating mirror such as a Montel mirror is used as the collimating optical element 11, the optical axis of the characteristic X-ray X c before passing through the collimating optical element 11 may not coincide with the optical axis of the characteristic X-ray X c after passing through the collimating optical element 11. In this case, in the following description, the optical axis of the characteristic X-ray X c before passing through the collimating optical element 11 is referred to as the first light-receiving axis L1.

[0030] (Measurement of magnetization inside the sample) The principle of measuring the magnetization inside the sample will be described with reference to FIG. 2.

[0031] In a normal magnetization measurement using the magnetization measurement apparatus 1, both the magnetization on the surface of the sample S and the magnetization inside the sample S are measured. This means that if the magnetization on the surface of the sample S can be made not to affect the measurement, it becomes possible to measure the magnetization inside the sample S.

[0032] Therefore, in the magnetization measurement apparatus 1, as shown in FIG. 2(a), the angle θ formed by the first light receiving axis L1 and the magnetization on the surface of the sample S is set to 90°. In other words, the characteristic X-ray X c whose traveling direction when emitted from the sample S forms a 90° angle with the magnetization on the surface of the sample S c is limited. As a result, the magnetization on the surface of the sample S can be made not to affect the measurement, and thus it becomes possible to measure the magnetization inside the sample S. This is because what is measured by the magnetization measurement apparatus 1 is the magnitude of the projection of the magnetization onto the first light receiving axis L1, and as shown in FIG. 2(b), this magnitude of the projection becomes approximately 0 when the angle θ formed by the first light receiving axis L1 and the magnetization on the surface of the sample S is 90°.

[0033] Note that in order to measure the magnetization inside the sample S, it is only necessary that the magnitude of the above projection be small enough to be negligible, and it is not necessary for the magnitude of the above projection to be exactly 0. Therefore, the angle formed by the first light receiving axis L1 and the magnetization on the surface of the sample S only needs to be close to 90° to the extent that the magnitude of the above projection can be ignored, for example, it may be 90° with integer precision.

[0034] (Sample to be measured) The sample S to be measured will be described with reference to FIG. 3.

[0035] The sample S to be measured is a magnetic material whose magnetization on the surface is substantially parallel to the surface. Here, "substantially parallel" means, for example, that the angle formed is 3° or less. Specific examples of such magnetic materials include electromagnetic steel sheets, high magnetostrictive materials (such as Fe-Ga alloys), nanocrystalline soft magnetic materials, and multilayer magnetic materials. Also, sintered magnets (such as Nd-Fe-B magnets, Sm-Co magnets, and ferrites) and bonded magnets (such as ferrites and Sm-Fe-N magnets) can also be regarded as specific examples of such magnetic materials when observing the plane including the magnetization direction.

[0036] In the case of Fe-Ga alloys, the magnetization may be inclined by about 10° from the surface. Even in such a case, by setting the angle formed between the first light-receiving axis L1 and the surface of the sample S to 90° (integer accuracy), there is an effect of suppressing the influence of surface magnetization on the measurement, and by setting the angle formed between the first light-receiving axis L1 and the surface magnetization to 90° (integer accuracy), this effect becomes remarkable. Here, the "angle formed between the first light-receiving axis L1 and the surface of the sample S" can be rephrased as the "angle formed between the first light-receiving axis L1 and the magnetization on the surface of the sample S". Also, in the case of Nd-Fe-B magnets, it is expected that there is a distribution of about 8° with a half-value half-width, for example, in the magnetization direction. Even in such a case, by setting the angle formed between the first light-receiving axis L1 and the surface of the sample S to 90° (integer accuracy), an effect of suppressing the influence of surface magnetization on the measurement can be obtained. Here, the "angle formed between the first light-receiving axis L1 and the surface of the sample S" can be rephrased as the "angle formed between the first light-receiving axis L1 and the magnetization direction of the surface of the sample S".

[0037] Such a sample S can be classified into (1) a sample S1 in which the magnetization on the surface is not substantially parallel to a specific axis parallel to the surface, and (2) a sample S2 in which the magnetization on the surface is substantially parallel to a specific axis parallel to the surface. Each of the above-described specific examples can be either sample S1 or sample S2.

[0038] FIG. 3(a) is a perspective view schematically showing a specific example of the sample S1. The sample S1 is composed of surface magnetic domains and internal magnetic domains (not shown). The direction of magnetization in each surface magnetic domain varies within a plane parallel to the surface of the sample S1 (the xy plane in FIG. 3(a)) and is not substantially parallel to a specific axis parallel to the surface of the sample S1.

[0039] The measurement of the magnetization inside the sample S1 according to this specific example is performed by setting the angle formed by the first light-receiving axis L1 and the surface of the sample S1 to 90°. Here, the “angle formed by the first light-receiving axis L1 and the surface of the sample S1” can be rephrased as the “angle formed by the first light-receiving axis L1 and the plane in which the magnetization extends on the surface of the sample S1”. In other words, the characteristic X-ray X c whose traveling direction when emitted from the sample S forms a 90° angle with the surface of the sample S c is limited to this. Thereby, the first light-receiving axis L1 is substantially orthogonal to the magnetization in each surface magnetic domain. For this reason, it becomes possible to measure the magnetization inside the sample S1 while suppressing the influence of the magnetization in each surface magnetic domain.

[0040] FIG. 3(b) is a perspective view schematically showing a specific example of the sample S2. The sample S2 is composed of surface magnetic domains and internal magnetic domains (not shown). The direction of magnetization in each surface magnetic domain is substantially parallel to a specific axis (the y-axis in FIG. 3(b)) parallel to the surface of the sample S2. Note that the magnetizations in adjacent surface magnetic domains are in opposite directions to each other.

[0041] The measurement of the magnetization inside the sample S2 according to this specific example is performed by setting the angle formed by the first light-receiving axis L1 and the specific axis to 90°. In other words, the characteristic X-ray X c whose traveling direction when emitted from the sample S forms a 90° angle with the specific axis cIt is limited to this. As a result, the first light-receiving axis L1 is substantially orthogonal to the magnetization in each surface magnetic domain. For this reason, it becomes possible to measure the magnetization inside the sample S2 while suppressing the influence of the magnetization in each surface magnetic domain. Here, the first light-receiving axis L1 only needs to be parallel to the xz plane in Fig. 3(b), and it is not necessary to be orthogonal to the surface of the sample S2. Therefore, it is also possible to measure the magnitude of the projection of the magnetization with respect to an axis that is not perpendicular to the surface of the sample S2. The same can be said even when the magnetizations in adjacent surface magnetic domains have the same direction and different magnitudes.

[0042] (Flow of magnetization measurement method) The flow of the measurement method M according to an embodiment of the present invention will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the flow of the measurement method M.

[0043] The measurement method M is a method for measuring the magnetization inside the sample S. As shown in Fig. 4, the measurement method M includes a first setting step M1, a first irradiation step M2, a first parallelization step M3, a first conversion step M4, a first reflection step M5, a first detection step M6, a second setting step M7, a second irradiation step M8, a second parallelization step M9, a second conversion step M10, a second reflection step M11, a second detection step M12, and a specific step M13. The measurement method M is implemented using, for example, the magnetization measurement device 1 described above.

[0044] The first setting step M1 is a step of setting the phase shifter 12 to perform conversion 1. Conversion 1 means, as described above, converting the right circular polarization component X R into the first linear polarization component X1 and converting the left circular polarization component X L into the second linear polarization component X2.

[0045] The first irradiation step M2 is a step of irradiating the excitation line P to the sample S using an excitation light source. The energy of the excitation line P is determined so that the excitation line P that has entered the inside of the sample S reaches a predetermined depth from the surface of the sample S. When the excitation line P is irradiated to the sample S in the first irradiation step M2, characteristic X-rays X cis emitted.

[0046] The first parallelization step M3 is a step of parallelizing the characteristic X-ray X obtained in the first irradiation step M2 using the parallelization optical element 11. c The characteristic X-ray X to be parallelized in the first parallelization step M3 c is the characteristic X-ray X emitted from the sample S c among which the traveling direction when exiting from the sample S forms a 90° angle with the magnetization direction on the surface of the sample S. c is as follows.

[0047] The first conversion step M4 is a step of converting two circular polarization components included in the characteristic X-ray X obtained in the first parallelization step M3 into two linearly polarized components with different polarization directions using the phase shifter 12. Specifically, it is a step of converting the right circular polarization component X c into the first linearly polarized component X1 and converting the left circular polarization component X R into the second linearly polarized component X2. The characteristic X-ray X to be converted in the first conversion step M4 L is the same as the characteristic X-ray X to be parallelized in the first parallelization step M3, c which is the characteristic X-ray X emitted from the sample S c among which the traveling direction when exiting from the sample S forms a 90° angle with the magnetization direction on the surface of the sample S. c is as follows. c is as follows.

[0048] The first reflection step M5 is a step of selectively reflecting a linearly polarized component having a specific polarization direction among the linearly polarized components included in the characteristic X-ray X' obtained in the first conversion step M4 using the two-crystal spectrometer 13. Specifically, it is a step of selectively reflecting the first linearly polarized component X1 derived from the right circular polarization component X c R R R

[0049] The first detection step M6 is a step of detecting the characteristic X-ray X c ” reflected in the first reflection step M5 using the detector 14. In the first reflection step M5, the right circular polarization component X RSince the first linearly polarized light component X1 derived from [source] is selectively reflected, in the first detection step M6, the right circularly polarized light component X R Characteristic X-ray X having the first linearly polarized light component X1 derived from [source] as the main component c ” is detected. In the first detection step M6, the control unit 15 records the intensity I c ” of the characteristic X-ray X + detected by the detector 14. This intensity I + is approximately proportional to the intensity I c of the right circularly polarized light component X R contained in the characteristic X-ray X R .

[0050] The second setting step M7 is a step of setting the phase shifter 12 to perform conversion 2. As described above, conversion 2 refers to converting the right circularly polarized light component X R into the second linearly polarized light component X2 and converting the left circularly polarized light component X L into the first linearly polarized light component X1.

[0051] The second irradiation step M8 is a step of irradiating the sample S with the excitation line P using the excitation light source. The energy of the excitation line P is determined in the same manner as in the first irradiation step M2. When the excitation line P is irradiated onto the sample S in the second irradiation step M8, characteristic X-ray X c is emitted from the sample S.

[0052] The second parallelization step M9 is a step of parallelizing the characteristic X-ray X c obtained in the second irradiation step M8 using the parallelization optical element 11. The characteristic X-ray X c to be parallelized in the second parallelization step M9 is the characteristic X-ray X c emitted from the sample S, and is the characteristic X-ray X c whose traveling direction when exiting the sample S forms a 90° angle with the direction of magnetization on the surface of the sample S.

[0053] The second conversion step M10 is a step of converting the two circularly polarized light components contained in the characteristic X-ray X c obtained in the second parallelization step M9 into two linearly polarized light components with different polarization directions using the phase shifter 12. Specifically, the right circularly polarized light component XR is converted into a second linearly polarized component X2, and the left circularly polarized component X L is converted into a first linearly polarized component X1. The characteristic X-ray X c to be converted in the second conversion step M10 is the characteristic X-ray X c to be parallelized in the second parallelization step M9. Similar to the characteristic X-ray X c emitted from the sample S, the characteristic X-ray X c is the one whose traveling direction when emitted from the sample S forms a 90° angle with the magnetization direction on the surface of the sample S.

[0054] The second reflection step M11 is a step of selectively reflecting a linearly polarized component having a specific polarization direction among the linearly polarized components included in the characteristic X-ray X c ' obtained in the second conversion step M10 using the two-crystal spectrometer 13. Specifically, it is a step of selectively reflecting the first linearly polarized component X1 derived from the left circularly polarized component X L .

[0055] The second detection step M12 is a step of detecting the characteristic X-ray X c ” reflected in the second reflection step M11 using the detector 14. In the second reflection step M11, since the first linearly polarized component X1 derived from the left circularly polarized component X L is selectively reflected, in the second detection step M12, the characteristic X-ray X L with the first linearly polarized component X1 derived from the left circularly polarized component X c as the main component is detected. In the second detection step M12, the control unit 15 records the intensity I c of the characteristic X-ray X - ” detected by the detector 14. This intensity I ー is approximately proportional to the intensity I c of the left circularly polarized component X L included in the characteristic X-ray X L .

[0056] The specific process M13 is a process of specifying the magnetization inside the sample S using the control unit 15 based on the intensity I + and the intensity I - . Specifically, the intensity I + and the intensity I- From the inversion ratio R’ = (I + - I - ) / (I + + I - ) is calculated. As described above, this inversion ratio R’ = (I + - I - ) / (I + + I - ) is the right circularly polarized light component X c contained in the characteristic X-ray X R with an intensity of I R , and the left circularly polarized light component X c contained in the characteristic X-ray X L with an intensity of I L , and the inversion ratio R = (I R - I L ) / (I R + I L ) calculated from it is approximately the same, and has a value corresponding to the magnitude of the projection of the magnetization inside the sample S onto the first light-receiving axis L1. For example, when the first light-receiving axis L1 is perpendicular to the surface of the sample S, this inversion ratio R’ = (I + - I - ) / (I + + I - ) has a value corresponding to the magnitude of the projection of the magnetization inside the sample S in the direction of the normal to the surface of the sample S. This is because, among the intensities I + , if the contribution from the surface magnetization is denoted as I + (surface), and the contribution from the internal magnetization is denoted as I + (internal), and among the intensities I ー , if the contribution from the surface magnetization is denoted as I - (surface), and the contribution from the internal magnetization is denoted as I - (internal), then I + (surface) - I - (surface) = 0, so the inversion ratio R’ is I + (internal) - I - (internal) / I + + I - .

[0057] As described above, the magnetization measurement method M is (1) among the characteristic X-rays X c emitted by the sample S, the characteristic X-rays X c whose traveling direction when emitted from the sample S forms a 90° angle with the magnetization on the surface of the sample S, and each circularly polarized light component X R,X L into conversion steps M4 and M10 that convert it into linearly polarized components with different polarization directions, and (2) for each circularly polarized component X R ,X L a specifying step M13 that specifies the magnetization inside the sample S based on the intensity of the linearly polarized component derived from

[0058] Therefore, according to the magnetization measurement method M, it is possible to prevent the magnetization on the surface of the sample S from being measured. As a result, the magnetization inside the sample S can be measured accurately.

[0059] Also, in the magnetization measurement method M, the above conversion step includes a first conversion step M4 that converts the right circularly polarized component X R into the first linearly polarized component X1 and converts the left circularly polarized component X L into the second linearly polarized component X2, and a second conversion step M10 that converts the right circularly polarized component X R into the second linearly polarized component X2 and converts the left circularly polarized component X L into the first linearly polarized component X1. Also, the specifying step M13 is a step of specifying the magnetization inside the sample S based on the intensity I + of the first linearly polarized component X1 obtained in the first conversion step M4 and the intensity I - of the first linearly polarized component X1 obtained in the second conversion step M10.

[0060] Therefore, according to the magnetization measurement method M, the intensity I R of the first linearly polarized component X1 derived from the right circularly polarized component X + , and the intensity I L of the first linearly polarized component X1 derived from the left circularly polarized component X - can be measured accurately respectively. Therefore, the magnetization inside the sample S can be measured more accurately.

[0061] (Region to be measured for magnetization) Regarding the region to be measured for magnetization in the sample S, it will be described with reference to FIG. 5. FIG. 5 is a cross-sectional view of the sample S.

[0062] In the sample S, the region to be measured for magnetization (hereinafter referred to as the "measurement target region") is a region where the excitation line P can enter and the characteristic X-ray X c can escape, excluding the surface magnetic domain. In FIG. 5, the measurement target region is illustrated by diagonal hatching. When synchrotron radiation X-rays are used as the excitation line P, the depth d of the measurement target region is from about several microns to about several tens of microns. When an electron beam such as a scanning electron microscope is used as the excitation line P, the depth d is several microns or less.

[0063] The depth d of the measurement target region can be adjusted by changing the energy of the excitation line P. Specifically, within a range not exceeding the depth of the region where the characteristic X-ray X c can escape, the higher the energy of the excitation line P, the larger the depth d of the measurement target region. Conversely, the lower the energy of the excitation line P, the smaller the depth d of the measurement target region. Therefore, if the magnetization measurement method M includes a step of changing the energy of the excitation line P, it becomes possible to adjust the depth d of the measurement target region to a desired value.

[0064] Also, the depth d of the measurement target region can be adjusted by changing the incident angle φ of the excitation line P. Specifically, within a range not exceeding the depth of the region where the characteristic X-ray X c can escape, the smaller the incident angle φ of the excitation line P, the larger the depth d of the measurement target region. Conversely, the larger the incident angle φ of the excitation line P, the shallower the depth d of the measurement target region. Therefore, if the magnetization measurement method M includes a step of changing the incident angle φ of the excitation line P, it becomes possible to adjust the depth d of the measurement target region to a desired value.

[0065] (Example) An example of the magnetization measurement method M using the magnetization measurement apparatus 1 will be described with reference to FIGS. 6 to 9. In this example, an electromagnetic steel sheet was used as the sample S. Also, in this example, synchrotron radiation X-rays of 26 keV were used as the excitation line P.

[0066] Figure 9 is a diagram of the three-dimensional magnetic domain structure predicted for the electromagnetic steel sheet used as sample S. The magnetization of the main magnetic domain is parallel to the surface of sample S regardless of whether it is on the surface or inside sample S. On the other hand, when abnormal magnetic domains other than the main magnetic domain occur, a surface abnormal magnetic domain (Lancet domain) with magnetization parallel to the surface of sample S, which is located on the surface of sample S, and an internal abnormal magnetic domain (transverse domain) with a magnetization component perpendicular to the surface of sample S, which is located inside sample S, are predicted to have a structure as shown in Figure 9.

[0067] Figure 8 is a magnetic domain map of sample S obtained with the angle between the optical axis of the excitation line P and the surface of sample S being 70° and the angle between the first light-receiving axis L1 and the surface of sample S being 90°. In this arrangement, the magnetization component parallel to the surface of sample S is suppressed, and the magnetization component perpendicular to the surface of sample S is emphasized. In the magnetic domain map shown in Figure 8, the white region (the region where the inversion ratio R' is positive) represents the region where the sum of the projected components of the detected magnetization (i.e., the normal component) is negative, and the black region (the region where the inversion ratio R' is negative) represents the region where the sum of the projected components of the detected magnetization (i.e., the normal component) is positive.

[0068] When compared with Figure 9, the white and black regions in the magnetic domain map of Figure 8 are interpreted as those where a transverse magnetic domain with a magnetization component perpendicular to the surface of sample S was observed. That is, it is interpreted as those where the magnetic domains inside sample S were observed.

[0069] Figure 7 is a magnetic domain map of sample S obtained with the angle between the optical axis of the excitation line P and the surface of sample S being 90° and the angle between the first light-receiving axis L1 and the surface of sample S being 70°. In this arrangement, both magnetization components parallel and perpendicular to the surface of sample S are measured. In the magnetic domain map shown in Figure 7, the white region (the region where the inversion ratio R' is positive) represents the region where the sum of the projected components of the detected magnetization is negative, and the black region (the region where the inversion ratio R' is negative) represents the region where the sum of the projected components of the detected magnetization is positive.

[0070] When compared with Figure 9, it can be seen that Figure 7 shows a result in which the main magnetic domain and the Lancet domain, which are magnetizations parallel to the surface, are clearly reflected as compared with Figure 8.

[0071] FIG. 6 is a magnetic domain map of the surface of the sample S obtained with the angle between the optical axis of the excitation line P and the surface of the sample S being 50° and the angle between the first light receiving axis L1 and the surface of the sample S being 110°. Compared with the arrangement in FIG. 7, since the angle between the first light receiving axis L1 and the surface of the sample S changes from an acute angle to an obtuse angle across 90°, the magnetization parallel to the surface of the sample S has the projection sign reversed compared to FIG. 7. In the magnetic domain map shown in FIG. 6, the white region (the region where the inversion ratio R' is positive) represents the region where the sum of the projection components of the detected magnetization is negative, and the black region (the region where the inversion ratio R' is negative) represents the region where the sum of the projection components of the detected magnetization is positive.

[0072] In FIG. 6, compared with FIG. 7, since the magnetization parallel to the surface of the sample S has the projection sign reversed, it can be seen that the signs are reversed in the magnetization of the main magnetic domain and the image of the Lancet magnetic domain.

[0073] Note that FIGS. 6 and 7 may also include information on the transverse magnetic domain. The in-plane component does not have its sign reversed like the magnetization parallel to the surface of the sample S under the conditions of FIG. 6 and FIG. 7. It can be seen from FIGS. 6 and 7 that there are portions where the sign is not reversed corresponding to the white and black regions of FIG. 8. This can be interpreted as reflecting the projection component of the transverse magnetic domain in the light receiving direction. On the other hand, although FIGS. 6 and 7 include information on the transverse magnetic domain, it can be seen that the internal magnetic domains can be observed more clearly under the conditions of FIG. 8.

[0074] (Supplementary Note) The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the respective technical means disclosed in the above-described embodiments are also included in the technical scope of the present invention.

[0075] 〔Summary〕 The magnetization measurement method according to Aspect 1 of the present invention includes a conversion step of converting each circular polarization component included in characteristic X-rays emitted from a sample, whose traveling direction when emitted from the sample forms a 90° angle with the magnetization on the surface of the sample, into linearly polarized light components with different polarization directions, and a specifying step of specifying the magnetization inside the sample based on the intensities of the linearly polarized light components derived from each circular polarization component obtained in the conversion step.

[0076] According to the above configuration, it is possible to prevent the magnetization on the surface of the sample from being measured. As a result, the magnetization inside the sample can be measured with high accuracy.

[0077] In the magnetization measurement method according to Aspect 2 of the present invention, in addition to the configuration of Aspect 1, the conversion step includes a first conversion step of converting the right circular polarization component into a first linearly polarized light component and converting the left circular polarization component into a second linearly polarized light component, and a second conversion step of converting the left circular polarization component into the first linearly polarized light component and converting the right circular polarization component into the second linearly polarized light component. The specifying step is a step of specifying the magnetization inside the sample based on the intensity of the first linearly polarized light component obtained in the first conversion step and the intensity of the first linearly polarized light component obtained in the second conversion step.

[0078] According to the above configuration, the intensities of the linearly polarized light components derived from each circular polarization component can be measured with higher accuracy. Therefore, the magnetization inside the sample can be measured with higher accuracy.

[0079] In the magnetization measurement method according to Aspect 3 of the present invention, in addition to the configuration of Aspect 1 or 2, the method further includes an adjustment step of adjusting the depth of the region to be measured for magnetization by changing the energy or the incident angle of the excitation beam irradiated on the sample to generate the characteristic X-rays.

[0080] According to the above configuration, the depth of the region to be measured for magnetization can be adjusted to a desired depth.

[0081] In the magnetization measurement method according to Aspect 4 of the present invention, in addition to the configuration of any one of Aspects 1 to 3, the configuration is adopted that the sample is a magnetic body in which the magnetization on the surface of the sample is substantially parallel to the surface.

[0082] According to the above configuration, the influence of the magnetization on the surface of the sample can be further suppressed, and the magnetization inside the sample can be measured with higher accuracy.

[0083] In the magnetization measurement method according to Aspect 5 of the present invention, in addition to the configuration of Aspect 4, the configuration is adopted that the sample is a magnetic body in which the magnetization on the surface of the sample is substantially parallel to an axis parallel to the surface.

[0084] According to the above configuration, not only the magnitude of the projection of the magnetization inside the sample onto the axis perpendicular to the surface of the sample but also the magnitude of the projection of the magnetization inside the sample onto the axis not perpendicular to the surface of the sample can be measured.

Explanation of Reference Numerals

[0085] 1 Magnetization measurement device 11 Parallelization optical element 12 Phase shifter 13 Two-crystal spectrometer 131 First crystal 132 Second crystal 14 Detector 15 Control unit

Claims

1. Among the characteristic X-rays emitted by the sample, a conversion step of converting each circular polarization component included in the characteristic X-rays whose traveling direction when emitted from the sample forms a 90° angle with the magnetization on the surface of the sample into linearly polarized light components with different polarization directions; A specifying step of specifying the magnetization inside the sample based on the intensities of the linearly polarized light components derived from each circular polarization component obtained in the conversion step. A magnetization measurement method characterized by the above.

2. The conversion step includes a first conversion step of converting the right circular polarization component into a first linearly polarized light component and converting the left circular polarization component into a second linearly polarized light component, and a second conversion step of converting the left circular polarization component into the first linearly polarized light component and converting the right circular polarization component into the second linearly polarized light component. The specifying step is a step of specifying the magnetization inside the sample based on the intensity of the first linearly polarized light component obtained in the first conversion step and the intensity of the first linearly polarized light component obtained in the second conversion step. The magnetization measurement method according to Claim 1, characterized by the above.

3. Further includes an adjustment step of adjusting the depth of the region to be measured for magnetization by changing the energy or incident angle of the excitation beam irradiated on the sample to generate the characteristic X-rays. The magnetization measurement method according to Claim 1 or 2, characterized by the above.

4. The sample is a magnetic material whose magnetization on the surface of the sample is substantially parallel to the surface. The magnetization measurement method according to any one of Claims 1 to 3, characterized by the above.

5. The sample is a magnetic material whose magnetization on the surface of the sample is substantially parallel to an axis parallel to the surface. The magnetization measurement method according to Claim 4, characterized by the above.

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