Magnetization measurement device and magnetization measurement method

Abstract

The present invention achieves a magnetization measuring device with which it is easy to maximize the measurement sensitivity or minimize measurement errors, and to set the depth of a measurement target point, of which the magnetization is to be measured, to a desired depth. A magnetization measuring device (1) is provided with: a phase shifter (12) which converts each circularly polarized light component contained in characteristic X-rays emitted by a sample (S) into linearly polarized light components having different polarization directions; a double-crystal spectrometer (13) which selectively reflects a linearly polarized light component having a specific polarization direction, a specific direction of travel, and a specific energy, from among the linearly polarized light components contained in the characteristic X-rays that have been transmitted through the phase shifter (12); and a detector (14) which detects the intensity of the linearly polarized light component reflected by the double-crystal spectrometer (13).

Description

[Technical Field]

[0001] The present invention relates to a magnetization measurement device and a magnetization measurement method for measuring the magnetization of a magnetic body. [Background technology]

[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. A known technology for measuring the spatial distribution of magnetization is, for example, the magnetization measurement device described in Patent Document 1 (referred to as a "magnetic material observation device" in Patent Document 1). When a magnetic material is irradiated with excitation rays, characteristic X-rays are generated. These characteristic X-rays contain a right-handed circularly polarized component and a left-handed circularly polarized component, and the magnetization at the point where the characteristic X-rays are generated can be determined 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] International Publication No. 2019 / 182097 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the magnetization measuring device described in Patent Document 1 still has some problems to be solved.

[0005] The first challenge is to optimize the optical system to maximize measurement sensitivity or minimize measurement errors. In the magnetization measurement device described in Patent Document 1, this optimization was insufficient. The second challenge is to measure the magnetization inside a magnetic body. In the magnetization measurement device described in Patent Document 1, the implementation of a method for measuring the magnetization inside a magnetic body was insufficient.

[0006] One aspect of the present invention has been made in consideration of the above-mentioned problems, and aims to realize a magnetization measurement device that can easily maximize measurement sensitivity or minimize measurement error, and can easily set the depth of the measurement point where magnetization is measured to a desired depth. [Means for solving the problem]

[0007] A magnetization measurement device according to one aspect of the present invention includes a retarder that converts each circularly polarized component contained in characteristic X-rays emitted by a sample into linearly polarized components with different polarization directions; a double-crystal monochromator that selectively reflects linearly polarized components having a specific polarization direction, a specific propagation direction, and a specific energy among the linearly polarized components contained in the characteristic X-rays that have passed through the retarder; and a detector that detects the intensity of the linearly polarized components reflected by the double-crystal monochromator. [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to realize a magnetization measurement device that can easily maximize measurement sensitivity or minimize measurement error, and set the depth of the measurement point where magnetization is measured to a desired depth. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing the configuration of a magnetization measurement device according to an embodiment of the present invention. [Figure 2] 1(a) is a schematic diagram showing first measurement conditions, and FIG. 1(b) is a schematic diagram showing second measurement conditions. FIG. 1(c) is a graph showing the energy dependence of the reversal ratio R' measured under the first measurement conditions using the magnetization measurement apparatus of FIG. 1 and the reversal ratio R' measured under the second measurement conditions using the magnetization measurement apparatus of FIG. 1. [Figure 3] 2 is a graph showing the energy dependence of the intensity difference I+-I- measured under first measurement conditions using the magnetization measurement device of FIG. 1, and the intensity difference I+-I- measured under second measurement conditions using the magnetization measurement device of FIG. 1. [Figure 4] This is a magnetic domain map created using the magnetization measurement device shown in Figure 1. [Figure 5] 1(a) is a schematic diagram showing the arrangement of a collimating optical element, a retarder, a double crystal monochromator, and a detector provided in the magnetization measurement device of Fig. 1 when measuring the magnetization of a point on the surface of a sample. FIG. 1(b) is a schematic diagram showing the arrangement of a collimating optical element, a retarder, a double crystal monochromator, and a detector provided in the magnetization measurement device of Fig. 1 when measuring the magnetization of a point inside a sample. [Figure 6] 1(a) is a schematic diagram showing the arrangement of a collimating optical element, a retarder, a double crystal monochromator, and a detector provided in the magnetization measurement device of Fig. 1 when measuring the magnetization of a point on the surface of a sample. FIG. 1(b) is a schematic diagram showing the arrangement of a collimating optical element, a retarder, a double crystal monochromator, and a detector provided in the magnetization measurement device of Fig. 1 when measuring the magnetization of a point inside a sample. [Figure 7] (a) is a schematic diagram showing one measurement condition. (b) is a graph showing the number n of characteristic X-rays incident on the detector, calculated by ray tracing, as a function of the depth d of the characteristic X-ray generation point, when the entire optical system is translated (shifted) so that the depth of the measurement point where magnetization is measured under the measurement condition shown in (a) is 0 μm, 6 μm, 13 μm, and 20 μm. [Figure 8] FIG. 2 is a schematic diagram showing an example of the settings of the magnetization measurement device shown in FIG. [Figure 9] (a) is a magnetic domain map on the surface of sample S obtained using the measurement device shown in Fig. 8. (b) is a magnetic domain map in a plane passing through lines AA, BB, CC, and DD and parallel to the XZ plane, obtained using the measurement device shown in Fig. 8. (c) is a diagram showing the boundary surfaces of internal magnetic domains of sample S estimated from the magnetic domain map shown in (b). DETAILED DESCRIPTION OF THE INVENTION

[0010] (Configuration of magnetization measurement 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.

[0011] The magnetization measurement device 1 is a device for measuring the magnetization of a sample S. The sample S is any magnetic material, for example, iron. When the sample S is irradiated with excitation rays P, characteristic X-rays X c Characteristic X-rays X c has a right-handed circularly polarized component X R and left-handed circularly polarized component X L The magnetization measurement device 1 includes a right-handed circularly polarized component X R Intensity I R and left-handed circularly polarized component X L Intensity I L The inversion ratio R = (I R -I L ) / (I R +I L ) from the characteristic X-rays X c The magnetization at the point of generation of the excitation ray P is identified. Here, identifying the magnetization refers to identifying one or both of the direction and magnitude of the magnetization. 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 X-ray beam is used as the excitation ray P.

[0012] 1, the magnetization measurement device 1 includes a collimating optical element 11, a retarder 12, a double crystal monochromator 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.

[0013] Right-handed circularly polarized component X emitted from sample S R and left-handed circularly polarized component X L Characteristic X-rays containing both c A collimating optical element 11 is disposed on the optical path of the characteristic X-rays X. cThe collimating optical element 11 is configured to collimate the characteristic X-rays X that have passed through 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. A Montel mirror is advantageous in that it can achieve a large solid angle of acceptance with a compact configuration. 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 the first light receiving axis L1.

[0014] The right-handed circularly polarized component X that has passed through the collimating optical element 11 R and left-handed circularly polarized component X L Characteristic X-rays containing both c A retarder 12 is disposed on the optical path of the characteristic X-rays X collimated by the collimating optical element 11. c Circularly polarized component X contained in R ,X L into linearly polarized components X1 and X2 having different polarization directions. Crystals such as silicon single crystal, germanium single crystal, and diamond single crystal can be used as the retarder 12. In this embodiment, diamond single crystal is used as the retarder 12. Diamond single crystal is superior to silicon single crystal and germanium single crystal in that it has high X-ray transmittance.

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

[0016] Transform 1: Right-handed circularly polarized component XR into the first linearly polarized component X1 and the left-handed circularly polarized component X L into a second linearly polarized component X2.

[0017] Transform 2: Right-handed circularly polarized component X R into the second linearly polarized component X2 and the left-handed circularly polarized component X L into a first linearly polarized component X1.

[0018] The magnetization measurement device 1 may further include a retarder rotation mechanism (not shown) that rotates the retarder 12 as described above. This allows the control unit 15 to control the retarder rotation mechanism, for example, to automate the rotation of the retarder 12. The retarder 12 may also be configured to be rotatable around the first light-receiving axis L1 as the rotation axis. In this case, by rotating the retarder 12 by 90°, it is possible to switch between performing the above-described transformation 1 and the above-described transformation 2.

[0019] Characteristic X-rays X1 and X2, which are transmitted through the retarder 12, contain both the first linearly polarized component X1 and the second linearly polarized component X2. c A double crystal monochromator 13 is arranged on the optical path of the phase retarder 12. The double crystal monochromator 13 divides the characteristic X-rays X c The double crystal monochromator 13 is configured to selectively reflect the linearly polarized component of the X-rays X′ having a specific polarization direction, a specific propagation direction, and a specific energy. c The optical fiber 100 is configured with a first crystal 131 that selectively reflects linearly polarized components having a specific polarization direction and specific energy out of the linearly polarized components reflected by the first crystal 131, and a second crystal 132 that further reflects linearly polarized components having a specific traveling direction out of the linearly polarized components reflected by the first crystal 131. Crystals such as silicon single crystal, germanium single crystal, and diamond single crystal can be used as the first crystal 131 and the second crystal 132. In this embodiment, germanium single crystal is used as the first crystal 131 and the second crystal 132, and its 400 plane is used as the reflecting surface. Hereinafter, the characteristic X-rays X reflected by the first crystal 131 will be referred to as c ”The optical axis of the characteristic X-rays X reflected by the second crystal 132 is also referred to as a second light-receiving axis L2. c ” This optical axis is also referred to as a 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 the first linearly polarized component X1 having a specific energy. The second crystal 132 is arranged to selectively reflect the first linearly polarized component X2 having a specific traveling direction. Therefore, when the retarder 12 performs the above-mentioned conversion 1, the double-crystal monochromator 13 selectively reflects the right-handed circularly polarized component X3. R On the other hand, when the retarder 12 performs the above transformation 2, the double crystal monochromator 13 selectively reflects the left-handed circularly polarized component X L The light selectively reflects linearly and circularly polarized light components having specific energy and specific propagation directions, which are derived from the above.

[0021] The first crystal 131 is rotatable about an axis perpendicular to the plane including the light-receiving axes L1 to L3. The second crystal 132 is rotatable about an axis parallel to the rotation axis of the first crystal 131. The first crystal 131 and the second crystal 132 are arranged in a ++ arrangement or a -- arrangement, and when 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-rays X incident on the first crystal 131 of the double crystal monochromator 13 are arranged in a ++ arrangement or a -- arrangement. c The characteristic X-rays X emitted from the second crystal 132 of the double crystal monochromator 13 and the point at infinity in the direction of the origin of the c The point at infinity in the direction of the end point of " is 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 reflecting plane of the first crystal 131 is used as the reflecting plane 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 characteristic X-rays X entering the double crystal monochromator 13 c The direction of travel of the X-rays and the characteristic X-rays X emitted from the double crystal monochromator 13 cThe 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] The magnetization measurement device 1 may further include a first crystal rotation mechanism that rotates the first crystal 131 around an axis that is perpendicular to the plane including the light-receiving axes L1 to L3, and a second crystal rotation mechanism that rotates the second crystal 132 around an axis that is parallel to the rotation axis of the first crystal 131. This allows the control unit 15 to control these crystal rotation mechanisms, for example, to automate the rotation of the first crystal 131 and the second crystal 132.

[0023] Characteristic X-rays X containing either the first linearly polarized component X1 or the second linearly polarized component X2 reflected by the double crystal monochromator 13 c The detector 14 is disposed on the optical path of the double crystal monochromator 13. The detector 14 detects the characteristic X-rays X reflected by the second crystal 132 of the double crystal monochromator 13. c The detector 14 is configured to detect the intensity of characteristic X-rays X . A semiconductor detector such as a germanium semiconductor detector or a silicon semiconductor detector can be used as the detector 14. In this embodiment, a silicon semiconductor detector, more specifically, a silicon drift detector, is used as the detector 14. Note that the detector 14 may also be a two-dimensional detector in which semiconductor detectors are arranged in a matrix. In this case, the detector 14 detects the intensity of characteristic X-rays X . c This allows adjustment according to the beam pattern of the

[0024] In this embodiment, the double crystal monochromator 13 is configured to selectively reflect the first linearly polarized component X1 having a specific energy. Therefore, when the retarder 12 performs the above-mentioned conversion 1, the detector 14 mainly receives the right-handed circularly polarized component X R On the other hand, when the retarder 12 performs the above conversion 2, the detector 14 mainly detects the left-handed circularly polarized component X LThe linearly and circularly polarized light component originating from the light having a specific energy is selectively detected.

[0025] The control unit 15 controls the retarder 12 to perform the above-mentioned conversion 1, and then converts the characteristic X-rays X detected by the detector 14 into c "Intensity I + As described above, when the retarder 12 performs the above conversion 1, the detector 14 mainly detects the characteristic X-rays X c Right-handed circularly polarized component X contained in R The linearly polarized component originating from is incident. Therefore, the intensity I + is the characteristic X-ray c Right-handed circularly polarized component X contained in R Intensity I R The control unit 15 controls the retarder 12 to perform the above-mentioned conversion 2, and then converts the intensity I of the characteristic X-rays detected by the detector 14 into - As described above, when the retarder 12 performs the above transformation 2, the detector 14 mainly receives the characteristic X-rays X c The left-handed circularly polarized component X contained in L The linearly polarized component originating from is incident. Therefore, the intensity I - is the characteristic X-ray c The left-handed circularly polarized component X contained in L Next, the control unit 15 calculates the intensity I + and Intensity I - From the inversion ratio R' = (I + -I - ) / (I + +I - ) is calculated. This inversion ratio R' = (I + -I - ) / (I + +I - ) is the characteristic X-ray c Right-handed circularly polarized component X contained in R Intensity I R , and characteristic X-rays X c The left-handed circularly polarized component X contained in L Intensity I L The reversal ratio R = (I R -I L ) / (I R +I LThe sign of the reversal ratio R' is approximately the same as that of the characteristic X-rays X c The magnitude of the reversal ratio R' represents the direction of the projection of the magnetization at the point of generation of the characteristic X-rays X c The control unit 15 uses this principle to calculate the magnitude of the projection of the magnetization at the point of generation of the characteristic X-rays X from the reversal ratio R'. c The projection of the magnetization at the point of generation onto the first light-receiving axis L1 is identified.

[0026] The magnetization measurement device 1 repeats the above-described measurement while changing the direction of the first light-receiving axis L1 relative to the sample S, thereby obtaining the characteristic X-rays X c The magnetization measuring device 1 can identify the direction and magnitude of magnetization at the point where characteristic X-rays X c By repeating the above-described measurement while changing the generating point of the magnetization, it is possible to identify the spatial distribution of magnetization in the sample S. For example, if the sample S is divided into multiple magnetic domains, the magnetization measurement device 1 can be used to create a magnetic domain map of the sample S.

[0027] (Maximizing measurement sensitivity and minimizing measurement error) The characteristic X-rays X selectively reflected by the first crystal 131 c ', that is, the characteristic X-rays X satisfying the Bragg reflection condition in the first crystal 131. c The energy of the characteristic X-rays X c The measurement sensitivity and measurement error of the magnetization measurement device 1 vary depending on the angle of incidence θ1 at which the characteristic X-rays X′ are incident on the first crystal 131. c Therefore, in the magnetization measurement device 1, a configuration is adopted in which the control unit 15 rotates the first crystal 131 to maximize the measurement sensitivity or minimize the measurement error.

[0028] To maximize the measurement sensitivity of the magnetization measurement device 1, the incident angle θ1 should be set so as to maximize the absolute value of the reversal ratio R'. More specifically, the control unit 15 repeats the above-described measurement while slightly rotating the first crystal 131 and changing the incident angle θ1 in increments of Δθ, and determines the incident angle θ that maximizes the absolute value of the reversal ratio R'. max Then, the control unit 15 determines the incident angle θ max The first crystal 131 is rotated so that the incident angle θ1 coincides with the incident angle θ1. Note that Δθ is a minute angle, typically on the order of 100 μrad (microradians). The range of variation of the incident angle θ1 is typically on the order of 1 mrad (milliradians).

[0029] A specific example of a method for maximizing the measurement sensitivity of the magnetization measurement apparatus 1 will be described with reference to FIG. 2. In this example, an iron plate was used as the sample S. The sample S was positioned so that the surface to be measured was parallel to the xy plane. In this example, synchrotron X-rays with an energy of 17.3 keV, a beam size (full width at half maximum) of 9.2 μm in the x-axis direction, and a beam size (full width at half maximum) of 7.4 μm in the y-axis direction were used as the excitation ray P. The excitation ray P was irradiated perpendicularly to the surface to be measured of the sample S, and the first light-receiving axis L1 was set so that the angle it formed with the surface to be measured was 60°.

[0030] In this specific example, the reversal ratio R' was calculated under first and second measurement conditions. The first measurement condition, as shown in Figure 2(a), is a measurement condition in which an external magnetic field +H in the positive direction of the x-axis is applied to the sample S, causing magnetization in the same direction in the sample S. The second measurement condition, as shown in Figure 2(b), is a measurement condition in which an external magnetic field -H in the negative direction of the x-axis is applied to the sample S, causing magnetization in the same direction in the sample S. The variation range of the incident angle θ1 was set to 5 mrad.

[0031] Fig. 2(c) is a graph showing the energy dependence of the reversal ratio R' measured under the first measurement condition and the reversal ratio R' measured under the second measurement condition. Fig. 2(c) shows that the reversal ratio R' measured under both measurement conditions is the same as that measured under the first measurement condition. cIt can be seen that the absolute value of the reversal ratio R' is maximized when the incident angle θ1 is set so that the first light receiving axis L1 and the magnetization direction are selectively reflected. In this specific example, the maximum absolute value of the reversal ratio R' reaches 12.4%. This means that when the first light receiving axis L1 and the magnetization direction are parallel, the maximum absolute value of the reversal ratio R' is approximately 25%.

[0032] In order to minimize the measurement error of the magnetization measurement device 1, the intensity difference I + -I - More specifically, the control unit 15 repeats the above-described measurement while slightly rotating the first crystal 131 to change the incident angle θ1 in increments of Δθ, and calculates the intensity difference I + -I - The angle of incidence θ' that maximizes the absolute value of max Then, the control unit 15 determines the incident angle θ′ determined by the incident angle θ1. max The first crystal 131 is rotated so that the incident angle θ1 coincides with the incident angle θ1. Note that Δθ is a minute angle, typically on the order of 100 μrad (microradians). The range of variation of the incident angle θ1 is typically on the order of 1 mrad (milliradians).

[0033] A specific example of a method for minimizing the measurement error of the magnetization measurement apparatus 1 will be described with reference to FIG. 3. In this example, an iron plate was used as the sample S. The sample S was positioned so that the surface to be measured was parallel to the xy plane. In this example, X-rays with an energy of 17.3 keV and a beam size (full width at half maximum) of 9.2 μm in the x-axis direction and 7.4 μm in the y-axis direction were used as the excitation ray P. The excitation ray P was irradiated perpendicularly onto the surface to be measured of the sample S, and the first light-receiving axis L1 was set so that the angle it formed with the surface to be measured was 60°.

[0034] In this specific example, the reversal ratio R' was calculated under the first and second measurement conditions. As described above, the first measurement condition is a measurement condition in which an external magnetic field +H in the positive direction of the x-axis is applied to the sample S, causing magnetization in the same direction in the sample S (see Figure 2(a)). As described above, the second measurement condition is a measurement condition in which an external magnetic field -H in the negative direction of the x-axis is applied to the sample S, causing magnetization in the same direction in the sample S (see Figure 2(b)). The variation range of the incident angle θ1 was set to 5 mrad.

[0035] Figure 3 shows the intensity difference I measured under the first measurement condition. + -I - and the intensity difference I measured under the second measurement condition + -I - 3 is a graph showing the energy dependence of the intensity difference I + -I - Not the strength itself, but the sum of the strength I + +I - The maximum value of (I + +I - ) peak The intensity difference normalized by I + -I - According to Figure 3, under all measurement conditions, the 6.4050 keV characteristic X-ray X c When the incident angle θ1 is set to selectively reflect ', the intensity difference I + -I - It can be seen that the absolute value of is maximum.

[0036] The energy (6.4053 keV) and intensity difference I + -I - The energy (6.4050 keV) that maximizes the inversion ratio R' is essentially the same as the incident angle θ max and the intensity difference I + -I - The incident angle θ' that maximizes max are substantially the same value. Therefore, the incident angle θ1 is set to the incident angle θ that maximizes the absolute value of the reversal ratio R'. max , intensity difference I + -I -The incident angle θ' that maximizes max , or incident angle θ max and the angle of incidence θ' max If the value is set to a value between these values, the measurement sensitivity of the magnetization measurement device 1 can be substantially maximized, and at the same time, the measurement error of the magnetization measurement device 1 can be substantially minimized.

[0037] Figure 4 shows magnetic domain maps M1 and M2 under the coating of an electrical steel sheet, created using the magnetization measurement device 1, which uses the above-mentioned method to substantially maximize measurement sensitivity and substantially minimize measurement error. Magnetic domain map M1 was created by dividing the 3 mm × 1.8 mm measurement field of view on the measurement surface of sample S into 30 μm × 30 μm cells and identifying the magnetization of each cell. Magnetic domain map M2 was created by dividing the 0.68 mm × 1.1 mm measurement field of view (part of the measurement field of magnetic domain map M1) into 10 μm × 10 μm cells and identifying the magnetization of each cell. Figure 4 shows that the above-mentioned method, which substantially maximizes measurement sensitivity and substantially minimizes measurement error, enables the creation of clear, highly accurate magnetic domain maps.

[0038] In order to maximize the measurement sensitivity and minimize the measurement error, it is preferable to rotate the second crystal 132 in conjunction with the first crystal 131. For 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 reflecting plane of the first crystal 131 is used as the reflecting plane of the second crystal 132, the rotation angle Δφ2 of the second crystal 132 should be Δφ2=3Δφ1, where Δφ1 is the rotation angle of the first crystal 131. This allows the characteristic X-rays X generated from the same point on the sample S to be rotated in a uniform direction. c can continue to detect.

[0039] However, in order to maximize the measurement sensitivity and minimize the measurement error, it is not necessary to use the second crystal 132. When the second crystal 132 is omitted, the second crystal 132 is used as the characteristic X-ray X c The detector 14 is moved away from the optical path of the first crystal 131 and the characteristic X-rays X cThe detector 14 can be configured to be rotatable around the rotation axis of the first crystal 131, and the light receiving surface of the detector 14 can always face the first crystal 131. Therefore, even if the first crystal 131 is rotated, the characteristic X-rays X reflected by the first crystal 131 can be c The detector 14 can always be placed on the optical path of the second crystal 132. c The detector 14 is moved away from the optical path of the first crystal 131 and the characteristic X-rays X c The results were obtained when the laser was placed on the optical path of the "

[0040] Furthermore, the characteristic X-rays X are collimated using the collimating optical element 11. c Instead of a configuration in which the characteristic X-rays are collimated (the traveling direction is aligned in a specific direction), a configuration in which a slit is used to extract a component having a specific traveling direction from the characteristic X-rays may be adopted. In this case, the slit is used to extract the characteristic X-rays X c ,X c ',X c In this case, the slit is a slit for irradiating the characteristic X-rays X within a plane parallel to the paper surface of FIG. c ,X c ',X c However, the second crystal 132 of the double crystal monochromator 13 is used to limit the characteristic X-rays X c When the slit is removed from the optical path of the ", the slit is set in a plane parallel to the paper surface of FIG. 1 and in a plane perpendicular to the paper surface of FIG. 1. c ,X c ',X c Use something that limits ".

[0041] (Other ideas for improving measurement sensitivity) Another method for improving the measurement sensitivity of the magnetization measurement device 1 is to use crystals with low angular resolution as the first crystal 131 and the second crystal 132. The angular resolution of a crystal can be achieved, for example, by curving the crystal or by disrupting the crystallinity of the crystal.

[0042] For example, the angular width of a light beam that can be reflected by the 400-plane of a germanium crystal is approximately 60 μrad when the angle of incidence is 45°. On the other hand, the angular width of a light beam that passes through a Montell mirror is approximately 120 μrad. Therefore, if the angular width of the reflectable light beam is increased by (1) replacing the germanium crystal with another crystal with lower angular resolution, (2) curving the germanium crystal, or (3) disrupting the crystallinity of the germanium crystal, the measurement sensitivity can be improved by up to about two times.

[0043] (Setting the depth of the measurement point) By rotating the first crystal 131 and the second crystal 132, the characteristic X-rays X incident on the detector 14 c It is possible to change the depth from the surface of the sample S of the generation point of the characteristic X-rays incident on the detector 14. In other words, by rotating the first crystal 131 and the second crystal 132, it is possible to change the depth from the surface of the sample S of the measurement point where the magnetization is measured. For this reason, the magnetization measurement device 1 employs a configuration in which the control unit 15 rotates the first crystal 131 and the second crystal 132 to set the depth from the surface of the sample S of the generation point of the characteristic X-rays that are incident on the detector 14.

[0044] When setting the depth of the measurement point, the second crystal 132 is also rotated in conjunction with the first crystal 131. For example, if the same single crystal as the first crystal 131 is used as the second crystal 132 and the same crystal plane as the reflecting surface of the first crystal 131 is used as the reflecting surface of the second crystal 132, the rotation angle Δφ2 of the second crystal 132 may be set to Δφ2 = Δφ1, where Δφ1 is the rotation angle of the first crystal 131. This makes it possible to change the depth of the measurement point while keeping the energy of the characteristic X-rays selectively reflected by the first crystal 131 and the second crystal 132 fixed (for example, while keeping it fixed to an energy that maximizes measurement sensitivity or minimizes measurement error).

[0045] FIG. 5(a) is a diagram showing the arrangement of the collimating optical element 11, the retarder 12, the double crystal monochromator 13, and the detector 14 when measuring the magnetization at point A on the surface of the sample S. In the arrangement shown in FIG. 5(a), the characteristic X-rays (shown by the solid line) generated at point A on the surface of the sample S satisfy the Bragg reflection condition at the first crystal 131 and the second crystal 132 and are reflected by the first crystal 131 and the second crystal 132. On the other hand, the characteristic X-rays (shown by the dashed line) generated at point B inside the sample S do not satisfy the Bragg reflection condition at the second crystal 132 and are not reflected by the second crystal 132. Therefore, the characteristic X-rays incident on the detector 14 are the characteristic X-rays generated at point A on the surface of the sample S. Therefore, the magnetization measured by the magnetization measurement device 1 is the magnetization at point A on the surface of the sample S.

[0046] FIG. 5B shows the arrangement of the collimating optical element 11, the retarder 12, the double-crystal monochromator 13, and the detector 14 when measuring the magnetization at point B inside the sample S. In the arrangement shown in FIG. 5B, compared to the arrangement shown in FIG. 5A, the first crystal 131 and the second crystal 132 are rotated slightly in the same direction by the same angle, on the order of 100 μrad (microradians). In the arrangement shown in FIG. 5B, the characteristic X-rays (shown by the dashed line) generated at point B inside the sample S satisfy the Bragg reflection condition at the first crystal 131 and the second crystal 132 and are reflected by the first crystal 131 and the second crystal 132. On the other hand, the characteristic X-rays (shown by the solid line) generated at point A on the surface of the sample S do not satisfy the Bragg reflection condition at the second crystal 132 and are not reflected by the second crystal 132. Therefore, the characteristic X-rays incident on the detector 14 are the characteristic X-rays generated at point B inside the sample S. Therefore, the magnetization measured by the magnetization measurement device 1 is the magnetization at point B inside the sample S.

[0047] As described above, by rotating the first crystal 131 and the second crystal 132, the characteristic X-rays X incident on the detector 14 cThe depth of the generation point from the surface of the sample S can be changed. In a typical setting, when the first crystal 131 and the second crystal 132 are rotated by a small amount on the order of 100 μrad (microradians), the characteristic X-rays X incident on the detector 14 are c The depth from the surface of the sample S where the magnetization occurs varies on the order of 10 μm (micrometers). When the sample S is iron, this method can typically measure the magnetization at any point at a depth of 50 μm or less from the surface of the sample S.

[0048] Note that the characteristic X-rays X incident on the detector 14 can also be adjusted by translating the collimating optical element 11. c It is possible to change the depth of the point of occurrence of the magnetization from the surface of the sample S. In other words, the depth of the measurement point at which the magnetization is measured from the surface of the sample S can be changed by translating the collimating optical element 11.

[0049] FIG. 6(a) is a diagram showing the arrangement of the collimating optical element 11, the retarder 12, the double crystal monochromator 13, and the detector 14 when measuring the magnetization at point A on the surface of the sample S. In the arrangement shown in FIG. 6(a), the characteristic X-rays (shown by the solid line) generated at point A on the surface of the sample S satisfy the Bragg reflection condition at the first crystal 131 and the second crystal 132 and are reflected by the first crystal 131 and the second crystal 132. On the other hand, the characteristic X-rays (shown by the dashed line) generated at point B inside the sample S do not satisfy the Bragg reflection condition at the second crystal 132 and are not reflected by the second crystal 132. Therefore, the characteristic X-rays incident on the detector 14 are the characteristic X-rays generated at point A on the surface of the sample S. Therefore, the magnetization measured by the magnetization measurement device 1 is the magnetization at point A on the surface of the sample S.

[0050] FIG. 6B shows the arrangement of the collimating optical element 11, the retarder 12, the double-crystal monochromator 13, and the detector 14 when measuring the magnetization at point B inside the sample S. In the arrangement shown in FIG. 6B, compared to the arrangement shown in FIG. 6A, the collimating optical element 11 is slightly translated in a direction in a plane including the first light-receiving axis L1, the second light-receiving axis L2, and the third light-receiving axis L3. In the arrangement shown in FIG. 6B, the characteristic X-rays (shown by the dashed line) generated at point B inside the sample S satisfy the Bragg reflection condition at the first crystal 131 and the second crystal 132 and are reflected by the first crystal 131 and the second crystal 132. On the other hand, the characteristic X-rays (shown by the solid line) generated at point A on the surface of the sample S do not satisfy the Bragg reflection condition at the second crystal 132 and are not reflected by the second crystal 132. Therefore, the characteristic X-rays incident on the detector 14 are the characteristic X-rays generated at point B inside the sample S. Therefore, the magnetization measured by the magnetization measurement device 1 is the magnetization at point B inside the sample S.

[0051] As described above, by translating the collimating optical element 11, the characteristic X-rays X incident on the detector 14 are c It is possible to change the depth of the generation point of the characteristic X-rays X from the surface of the sample S. It should be noted that even if the entire optical system consisting of the collimating optical element 11, the retarder 12, the double crystal monochromator 13, and the detector 14 is translated, rather than just translating the collimating optical element 11, the characteristic X-rays X incident on the detector 14 can be changed. c The depth of the generation point of the characteristic X-rays X incident on the detector 14 can be changed from the surface of the sample S. In addition, instead of translating the entire optical system consisting of the collimating optical element 11, the retarder 12, the double crystal monochromator 13, and the detector 14, the sample S can be translated. c The depth from the surface of the sample S at which the point of generation can be changed.

[0052] Figure 7(b) is a graph showing the number n of characteristic X-rays incident on the detector 14, calculated by ray tracing, as a function of the depth d of the characteristic X-ray source when the entire optical system is translated (shifted) so that the depth of the measurement point where magnetization is measured is 0 μm, 6 μm, 13 μm, and 20 μm. For the ray tracing calculation, an iron plate was assumed as the sample S. The excitation ray P was assumed to be an X-ray with an energy of 26 keV and a beam size (full width at half maximum) of 1 μm. As shown in Figure 7(a), the optical axis of the excitation ray P was set to form a 45° angle with the measurement surface, and the first light-receiving axis L1 was set to form a 45° angle with the measurement surface. The first crystal 131 and the second crystal 132 were germanium single crystals that reflected the characteristic X-rays at their 400° planes.

[0053] Figure 7(b) shows that when the entire optical system is positioned so that the depth of the measurement point where magnetization is measured is 0 μm, the number of light rays n reaches a maximum at a depth d = 0 μm and decreases sharply as the depth d increases from 0 μm. This confirms that the characteristic X-rays generated from the point at a depth d = 0 μm can be selectively detected. Figure 7(b) also shows that when the entire optical system is shifted so that the depth of the measurement point where magnetization is measured is 6 μm, the number of light rays n reaches a maximum at a depth d = 6 μm and decreases sharply as the depth d decreases from 6 μm. This confirms that the characteristic X-rays generated from the point at a depth d = 6 μm can be selectively detected. The same holds true when the entire optical system is shifted so that the depth of the measurement point where magnetization is measured is 13 μm or 20 μm. The full width at half maximum of each graph shown in Figure 7(b) is approximately 5 μm. Therefore, it is understood that the resolution in the depth direction of the magnetization measuring device 1 is about 5 μm.

[0054] (Use of position-resolved detectors) By using a position-resolved detector as the detector 14, it becomes possible to specify the magnetization at a plurality of positions on the sample S, that is, to specify the magnetization distribution, using the control unit 15. In this case, it is preferable to use a shielding plate with slits formed thereon instead of the collimating optical element 11. This shielding plate is used to block the characteristic X-rays X c ,X c ',X c The slit can be placed anywhere on the optical path of the ". The slit is also placed in a plane parallel to the paper surface of FIG. 1 so that the characteristic X-rays X c ,X c ',X c Anything that has the function of restricting the magnetization distribution can be used. By using a shielding plate with a slit formed therein, it is possible to measure the magnetization distribution on the line that the slit can see in the sample S. In this case, a one-dimensional position-resolved detector can be used as the detector 14. Here, the location to be measured for magnetization may be the surface of the sample S, or may be inside the sample S, or may be partly on the surface of the sample S and the rest inside the sample S.

[0055] (Example of internal magnetization measurement) An example of measuring the internal magnetization will be described with reference to FIGS.

[0056] Fig. 8 is a schematic diagram showing the settings of the magnetization measurement apparatus 1. In this measurement example, as shown in Fig. 8, the angle formed between the optical axis of the excitation ray P and the surface of the sample S was set to 30°, and the angle formed between the first light-receiving axis L1 and the surface of the sample S was set to 60°. An electromagnetic steel sheet was used as the sample S, and 26 keV X-rays were used as the excitation ray P. Furthermore, germanium single crystals were used as the first crystal 131 and the second crystal 132, and their 400 planes were used as reflecting surfaces.

[0057] First, the sample S is translated in the Y-axis direction and the Z-axis direction (see FIG. 8) relative to the magnetization measurement device 1, so that the characteristic X-rays X cThe magnetization was measured while moving the generation point of the magnetic field, and a magnetic domain map of the surface of sample S was created. The created magnetic domain map is shown in Figure 9(a). In this magnetic domain map, black areas represent magnetic domains (hereinafter referred to as "first magnetic domains") whose magnetization is oriented so that their projection onto the first light-receiving axis L1 is positive, and white areas represent magnetic domains (hereinafter also referred to as "second magnetic domains") whose magnetization is oriented so that their projection onto the first light-receiving axis L1 is negative.

[0058] Next, the sample S is translated in the X-axis direction and the Z-axis direction (see FIG. 8) relative to the magnetization measurement device 1, so that the characteristic X-rays X c While moving the magnetization generation point, we measured the magnetization for each 0.01 mm (Z-axis direction) x 0.01 mm (X-axis direction) cell, and created a magnetic domain map for a plane that includes the AA line and is parallel to the ZX plane. Similarly, we created magnetic domain maps for a plane that includes the BB line and is parallel to the ZX plane, a plane that includes the CC line and is parallel to the ZX plane, and a plane that includes the DD line and is parallel to the ZX plane. The four magnetic domain maps created are shown in Figure 9(b). Looking at these four magnetic domain maps, we can see that the first magnetic domain, which was exposed on the surface at the AA line, gradually sinks deeper as we move away from the AA line to the BB, CC, and DD lines.

[0059] Finally, the boundary surface between the first and second magnetic domains, estimated from the magnetic domain map measured as described above, is shown in Figure 9(c). This confirmed that the internal magnetic domains of an electromagnetic steel sheet can be measured using the magnetization measurement device 1. It was also confirmed that the resolution in the depth direction of the magnetization measurement device 1 is sufficient to estimate the boundaries of the internal magnetic domains of an electromagnetic steel sheet.

[0060] (Additional notes) The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the above-described embodiments are also included in the technical scope of the present invention.

[0061] 〔summary〕 A magnetization measurement device according to a first aspect of the present invention includes a retarder that converts each circularly polarized component contained in characteristic X-rays emitted by a sample into linearly polarized components with different polarization directions, a double-crystal monochromator that selectively reflects linearly polarized components having a specific polarization direction, a specific propagation direction, and a specific energy among the linearly polarized components contained in the characteristic X-rays that have passed through the retarder, and a detector that detects the intensity of the linearly polarized components reflected by the double-crystal monochromator.

[0062] According to the above configuration, by rotating the first crystal included in the double crystal monochromator, it is possible to maximize measurement sensitivity or minimize measurement errors. Also, according to the above configuration, by rotating the first crystal and the second crystal included in the double crystal monochromator, it is possible to set the depth (distance from the surface of the magnetic body) of the measurement point where magnetization is measured to a desired depth.

[0063] A magnetization measurement device according to a second aspect of the present invention has the same configuration as the magnetization measurement device according to the first aspect, and further includes a control unit that rotates a first crystal included in the double crystal monochromator and rotates or moves a second crystal included in the double crystal monochromator out of the optical path of the characteristic X-rays reflected by the first crystal, thereby maximizing the absolute value of the difference or inversion ratio between the intensity of the characteristic X-rays detected by the detector when the first crystal selectively reflects the linearly polarized component derived from the right-handed circularly polarized component and the intensity of the specific X-rays detected by the detector when the first crystal selectively reflects the linearly polarized component derived from the left-handed circularly polarized component.

[0064] According to the above configuration, it is possible to maximize measurement sensitivity or minimize measurement errors.

[0065] A magnetization measurement device according to a third aspect of the present invention has the same configuration as the magnetization measurement device according to the first aspect, and further includes a collimating optical element that collimates the characteristic X-rays incident on the retarder, and a control unit that sets the depth from the surface of the sample of the generation point of the characteristic X-rays incident on the detector by rotating the first crystal and the second crystal included in the double crystal monochromator.

[0066] According to the above configuration, the depth of the measurement point at which the magnetization is measured can be set to a desired depth.

[0067] A magnetization measurement device according to a fourth aspect of the present invention has the same configuration as the magnetization measurement device according to the first aspect, and further includes a collimating optical element that collimates the characteristic X-rays incident on the retarder, and a control unit that sets the depth from the surface of the sample of the generation point of the characteristic X-rays incident on the detector by translating the sample or the collimating optical element.

[0068] According to the above configuration, the depth of the measurement point at which the magnetization is measured can be set to a desired depth.

[0069] A magnetization measuring device according to aspect 5 of the present invention is further provided with a control unit that identifies the magnetization at multiple positions of the sample based on the output of the detector, and the detector is a position-resolved detector.

[0070] According to the above configuration, it is possible to identify the magnetization at a plurality of positions on the sample without performing operations such as translating the sample, etc. The positions to be measured may be different positions in the in-surface direction of the sample, different positions in the depth direction of the sample, or different positions both in the in-surface direction of the sample and in the depth direction of the sample.

[0071] A magnetization measurement device according to a sixth aspect of the present invention has the same configuration as the magnetization measurement device according to any one of the first to fifth aspects, and further has a configuration in which the retarder is configured to be switchable between converting either a right-handed circularly polarized component or a left-handed circularly polarized component contained in characteristic X-rays emitted by a sample into a linearly polarized component having the specific polarization direction.

[0072] According to the above configuration, it is possible to easily switch between detecting the linearly polarized component derived from the right-handed circularly polarized component and detecting the linearly polarized component derived from the left-handed circularly polarized component.

[0073] A magnetization measurement method according to a seventh aspect of the present invention is a magnetization measurement method using a magnetization measurement device according to the first aspect, which includes a step of rotating a first crystal included in the double crystal monochromator and rotating or retracting a second crystal included in the double crystal monochromator from the optical path of the characteristic X-rays reflected by the first crystal, thereby maximizing the absolute value of the difference or inversion ratio between the intensity of the characteristic X-rays detected by the detector when the first crystal selectively reflects linearly polarized light derived from right-handed circularly polarized light and the intensity of the specific X-rays detected by the detector when the first crystal selectively reflects linearly polarized light derived from left-handed circularly polarized light.

[0074] According to the above method, it is possible to maximize the measurement sensitivity or minimize the measurement error.

[0075] A magnetization measurement method according to aspect 8 of the present invention is a magnetization measurement method using the magnetization measurement device according to aspect 1, which further includes a collimating optical element that collimates the characteristic X-rays incident on the phase retarder, and includes a step of setting the depth from the surface of the sample of the generation point of the characteristic X-rays incident on the detector by rotating the first crystal and the second crystal included in the double crystal spectrometer.

[0076] According to the above method, the depth of the measurement point where the magnetization is measured can be set to a desired depth.

[0077] A magnetization measurement method according to aspect 9 of the present invention is a magnetization measurement method using the magnetization measurement device according to aspect 1, which further includes a collimating optical element that collimates the characteristic X-rays incident on the phase retarder, and includes a step of setting the depth from the surface of the sample of the generation point of the characteristic X-rays incident on the detector by translating the sample or the collimating optical element.

[0078] According to the above method, the depth of the measurement point where the magnetization is measured can be set to a desired depth.

[0079] A magnetization measurement method according to aspect 10 of the present invention is a magnetization measurement method using a magnetization measurement device according to aspect 1, which includes a step of identifying magnetization at multiple positions on the sample based on the output of the detector, and the detector is a position-resolved detector.

[0080] According to the above method, it is possible to identify the magnetization at a plurality of positions on the sample without performing operations such as translating the sample, etc. The positions to be measured may be different positions in the in-surface direction of the sample, different positions in the depth direction of the sample, or different positions both in the in-surface direction and in the depth direction of the sample. [Explanation of symbols]

[0081] 1 Magnetization measuring device 11 Collimating optical elements 12 Phase shifter 13 Double crystal spectrometer 131 First Crystal 132 Second Crystal 14 Detector 15 Control Unit

Claims

1. a collimating optical element for collimating the characteristic X-rays emitted by the sample; a retarder that converts each circularly polarized component included in the characteristic X-rays collimated by the collimating optical element into a linearly polarized component having a different polarization direction; a double crystal monochromator that selectively reflects linearly polarized components having a specific polarization direction, a specific propagation direction, and a specific energy among the linearly polarized components contained in the characteristic X-rays that have passed through the retarder; a detector for detecting the intensity of the linearly polarized light component reflected by the double crystal monochromator; a control unit that sets the depth from the surface of the sample of a point of origin of characteristic X-rays incident on the detector by rotating a first crystal and a second crystal included in the double crystal monochromator, the rotation of the first crystal is a rotation about a line that passes through the first crystal and is perpendicular to a plane that includes the optical axis of the characteristic X-ray transmitted through the retarder, the optical axis of the linearly polarized component reflected by the first crystal, and the optical axis of the linearly polarized component reflected by the second crystal, the rotation of the second crystal is a rotation about a straight line that is perpendicular to the plane and passes through the second crystal, the collimating optical element and the double crystal monochromator function as a selection means for selecting a point of origin of characteristic X-rays incident on the detector; A magnetization measurement device characterized by:

2. The double crystal monochromator further includes a control unit that rotates a first crystal included in the double crystal monochromator and rotates or moves a second crystal included in the double crystal monochromator away from the optical path of the characteristic X-rays reflected by the first crystal, thereby maximizing the absolute value of the difference or inversion ratio between the intensity of the characteristic X-rays detected by the detector when the first crystal selectively reflects the linearly polarized component derived from the right-handed circularly polarized component and the intensity of the specific X-rays detected by the detector when the first crystal selectively reflects the linearly polarized component derived from the left-handed circularly polarized component.

2. The magnetization measuring device according to claim 1.

3. a control unit that sets a depth from a surface of the sample of a generation point of characteristic X-rays incident on the detector by translating the sample or the collimating optical element relative to the retarder, the double crystal monochromator, and the detector, the translation of the collimating optical element is a direction within a plane including an optical axis of the characteristic X-ray transmitted through the retarder, an optical axis of the linearly polarized component reflected by a first crystal included in the double crystal monochromator, and an optical axis of the linearly polarized component reflected by a second crystal included in the double crystal monochromator, and is a translation in a direction intersecting the optical axis of the characteristic X-ray transmitted through the retarder.

2. The magnetization measuring device according to claim 1.

4. the retarder is configured to be switchable between converting either a right-handed circularly polarized component or a left-handed circularly polarized component contained in characteristic X-rays emitted by a sample into a linearly polarized component having the specific polarization direction.

4. The magnetization measuring device according to claim 1, wherein the magnetization measuring device is a magnetization measuring device.

5. 2. A magnetization measurement method using the magnetization measurement device according to claim 1, the step of rotating a first crystal included in the double crystal monochromator and rotating or retracting a second crystal included in the double crystal monochromator from the optical path of the characteristic X-rays reflected by the first crystal, thereby maximizing the absolute value of the difference or inversion ratio between the intensity of the characteristic X-rays detected by the detector when the first crystal selectively reflects linearly polarized light derived from right-handed circularly polarized light and the intensity of the specific X-rays detected by the detector when the first crystal selectively reflects linearly polarized light derived from left-handed circularly polarized light. A magnetization measurement method characterized by:

6. 2. A magnetization measurement method using the magnetization measurement device according to claim 1, a step of rotating a first crystal and a second crystal included in the double crystal monochromator to set a depth from the surface of the sample of a point of origin of characteristic X-rays incident on the detector, the rotation of the first crystal is a rotation about a line that passes through the first crystal and is perpendicular to a plane that includes the optical axis of the characteristic X-ray transmitted through the retarder, the optical axis of the linearly polarized component reflected by the first crystal, and the optical axis of the linearly polarized component reflected by the second crystal, The rotation of the second crystal is a rotation about a straight line that is perpendicular to the plane and passes through the second crystal. A magnetization measurement method characterized by:

7. 2. A magnetization measurement method using the magnetization measurement device according to claim 1, a step of setting a depth from a surface of the sample of a generation point of characteristic X-rays incident on the detector by translating the sample or the collimating optical element relative to the retarder, the double crystal monochromator, and the detector, the translation of the collimating optical element is a direction within a plane including an optical axis of the characteristic X-ray transmitted through the retarder, an optical axis of the linearly polarized component reflected by a first crystal included in the double crystal monochromator, and an optical axis of the linearly polarized component reflected by a second crystal included in the double crystal monochromator, and is a translation in a direction intersecting the optical axis of the characteristic X-ray transmitted through the retarder. A magnetization measurement method characterized by:

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