Method and apparatus for measuring the magnetic properties of soft magnetic materials

Abstract

This invention provides a measurement method and apparatus that can significantly reduce the time required for measurement of magnetic properties using a diamond NVC sensor compared to conventional methods. [Solution] The magnetic property measurement apparatus for a soft magnetic material according to the present invention comprises a sample setting mechanism, a measurement sample magnetic field application mechanism, a diamond NVC sensor, a laser light irradiation mechanism, a microwave irradiation mechanism, a photodetection magnetic resonance spectrum measurement mechanism, and a control / data analysis mechanism. The control / data analysis mechanism is configured to perform a measurement condition input step, a magnetic property measurement step, and a data analysis step. The measurement conditions include the range of the external magnetic field H0 and the permeability μ of the measurement sample. smp , and a predetermined frequency sweep width Δω in the microwave, wherein the predetermined frequency range of the microwave in the magnetic property measurement step is "ω" in an environment of 20°C. d = 2.87 ± 28 × μ smp The microwave frequency ω can be determined from the relationship "x H0". d Based on "ω" d It is characterized by being in the region ±Δω.

Description

[Technical Field]

[0001] The present invention relates to a technique for measuring material properties, and more particularly to a method for measuring the magnetic properties of a soft magnetic material and a measuring apparatus for performing the said measurement method. [Background technology]

[0002] In recent years, from the perspective of protecting the global environment, the application fields of electromechanical devices that utilize iron cores (e.g., rotating electric machines and transformers) have been expanding, and consequently, there has been a very strong demand for higher output, higher efficiency, and miniaturization of such electromechanical devices. Laminated iron cores, which are made by laminating multiple soft magnetic material plates (e.g., 0.01 to 3 mm thick), are widely used as the iron cores for such electromechanical devices.

[0003] When considering a rotating electric machine as an electromechanical device, its output is proportional to the product of the torque and rotational speed during operation. Therefore, increasing either the torque or the rotational speed can increase the output. Torque is proportional to the product of the magnetic flux density and the current value. To increase torque, it is desirable to use a soft magnetic material that achieves a high saturation magnetic flux density Bs and / or a high saturation magnetization Ms. Various methods are employed to control the composition and microstructure of soft magnetic materials in order to increase Bs / Ms.

[0004] When increasing the rotational speed during operation, the conversion efficiency between electrical and magnetic energy is crucial, and reducing losses (iron loss Pi) in soft magnetic materials becomes a challenge. Reducing Pi also leads to suppression of heat generation during operation. Pi is the sum of hysteresis loss and eddy current loss. To reduce hysteresis loss, a low coercivity Hc is desirable, and to reduce eddy current loss, increasing electrical resistance (e.g., alloying) or reducing the eddy current area (e.g., thinning the plate) is effective.

[0005] For the measurement of magnetic properties, measurements using a vibrating sample magnetometer (VSM) or the Epstein method have been widely used conventionally. However, the measurement of magnetic properties using a VSM or the Epstein method has weaknesses in that its accuracy is about ±0.1% and there are restrictions on the sample shapes that can be measured. From the perspective of developing higher-performance soft magnetic materials, a measurement method that can enhance the measurement accuracy of magnetic properties compared to the conventional measurements using a VSM or the Epstein method is desirable. Also, naturally, it is desirable that there are fewer restrictions on the sample shapes that can be measured.

[0006] In response to such requirements, quantum magnetic sensors that utilize the electron spin quantum states of nitrogen-vacancy centers (NVCs) in diamond crystals have attracted attention in recent years because of their characteristics of excellent magnetic detection sensitivity and spatial resolution.

[0007] For example, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2021-152473) teaches a device configuration in which NVCs are applied to magnetic memory inspection.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Non-Patent Documents

[0009]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0010] The quantum magnetic sensor (hereinafter referred to as "diamond NVC sensor") that utilizes the electron spin quantum state of the nitrogen-vacancy center (NVC) in the diamond crystal described above has an excellent feature that its accuracy is one digit higher (about ±0.01%) than the measurement by the conventional VSM or Epstein method.

[0011] However, the measurement of magnetic properties using the diamond NVC sensor has a weakness that the time required for measurement is more than one digit longer (for example, 20 to 30 times) than the measurement by the conventional VSM or Epstein method. In other words, the measurement of magnetic properties using the diamond NVC sensor has been considered unsuitable for measurements with a large number of samples.

[0012] The inventors of the present invention have diligently worked on the technical development of the measurement of magnetic properties using the diamond NVC sensor in order to effectively utilize the attractive feature of the diamond NVC sensor, which has high measurement accuracy. Therefore, the primary object of the present invention is to provide a measurement method and a measurement device that can significantly shorten the time required for measurement in the measurement of magnetic properties using the diamond NVC sensor as compared with the prior art.

Means for Solving the Problems

[0013] (I) One aspect of the present invention is a method for measuring the magnetic properties of a soft magnetic material using a diamond NVC sensor, comprising: a measurement condition input step of inputting the measurement conditions of the magnetic properties; A magnetic property measurement step in which, in accordance with the above measurement conditions, an external magnetic field is applied to the measurement sample of the soft magnetic material, and the diamond NVC sensor disposed on the measurement sample is irradiated with green laser light and microwaves in a predetermined frequency range, and the dip in the photodetectable magnetic resonance spectrum is measured by detecting red fluorescence from the diamond NVC sensor. The system includes a data analysis step of determining the center frequency of the dip and calculating the magnetic field of the measurement sample in the external magnetic field from the center frequency, The measurement conditions are the range of the external magnetic field H0 [unit: A / m] and the permeability μ of the measurement sample. smp [Unit: T·m / A] and a predetermined frequency sweep width Δω in the microwave, The predetermined frequency range of the microwave in the magnetic property measurement step is In a 20℃ environment, "ω d = 2.87 ± 28 × μ smp The microwave frequency ω of the aforementioned dip can be determined from the relationship ω × H0. d [Unit: GHz] based on "ω" d This is the region ±Δω. This invention provides a method for measuring the magnetic properties of a soft magnetic material, characterized by the following features.

[0014] (II) Another aspect of the present invention is a device for measuring the magnetic properties of a soft magnetic material, A sample setting mechanism for setting the soft magnetic material that will be used as a measurement sample, A measurement sample magnetic field application mechanism for applying an external magnetic field to the measurement sample, A diamond NVC sensor for detecting the magnetic field of the sample being measured, A laser beam irradiation mechanism that irradiates the diamond NVC sensor with green laser light, A microwave irradiation mechanism that irradiates the diamond NVC sensor with predetermined microwaves, A photodetectable magnetic resonance spectrum measurement mechanism that detects red fluorescence from the diamond NVC sensor and measures the photodetectable magnetic resonance spectrum, A control and data analysis mechanism that controls the measurement sample magnetic field application mechanism, the laser light irradiation mechanism, and the microwave irradiation mechanism, and analyzes data from the photo-detection magnetic resonance spectrum measured by the photo-detection magnetic resonance spectrum measurement mechanism. The control and data analysis mechanism A measurement condition input step for inputting the measurement conditions of the magnetic properties. Along with the measurement conditions, apply and control the external magnetic field to the measurement sample, irradiate and control the green laser light and the microwave to the diamond NVC sensor, and measure the dip of the photo-detection magnetic resonance spectrum by the red fluorescence from the diamond NVC sensor. A magnetic property measurement step. A data analysis step of obtaining the center frequency of the dip and calculating the magnetic field of the measurement sample in the external magnetic field from the center frequency. Is configured to execute The measurement conditions include the range of the external magnetic field H0 [unit: A / m], the magnetic permeability μ of the measurement sample smp [unit: T·m / A], and a predetermined frequency sweep width Δω in the microwave. The predetermined frequency range of the microwave in the magnetic property measurement step In an environment of 2C, "ω d = 2.87 ± 28 × μ smp × H0", the microwave frequency ω of the dip obtained from the relational expression d [unit: GHz], based on "ω d ±Δω" region. A magnetic property measurement device for a soft magnetic material, characterized by the above.

[0015] In the above magnetic property measurement method (I) and magnetic property measurement device (II) of the present invention, the following improvements and changes can be freely combined and added. (i) The measurement condition input step The magnetic permeability μ of the measurement sample smpA substep for inputting measurement conditions other than those specified, Based on the measurement conditions in the aforementioned measurement condition partial input substep, the external magnetic field is applied to the measurement sample, and while irradiating the diamond NVC sensor with the green laser light and the microwave, the dip in the photodetectable magnetic resonance spectrum is measured and the center frequency of the dip is determined in the photodetectable magnetic resonance spectrum preliminary measurement substep. From the applied external magnetic field, the center frequency of the dip determined, and the relational equation, the permeability μ of the measurement sample is obtained. smp A substep for calculating the sample permeability, It is divided and executed in parts. (ii) The measurement conditions further include the frequency sweep rate of the microwave, The external magnetic field in the photodetection magnetic resonance spectrum preliminary measurement substep is at least one magnetic field selected from 20% to 80% of the range of the external magnetic field input in the measurement condition partial input substep. In the photodetection magnetic resonance spectrum preliminary measurement substep, the microwave irradiation is performed at a speed of 5 to 10 times the frequency sweep rate input in the measurement condition partial input substep. (iii) The magnetic property measurement step is performed on either "only the region below 2.87 GHz" or "only the region above 2.87 GHz" of the Zeeman-split dip. (iv) The predetermined frequency sweep width Δω is 0.01 GHz or more and 0.05 GHz or less. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a measurement method and measuring apparatus that significantly reduces the time required for measurement in magnetic property measurement using a diamond NVC sensor compared to conventional methods. Other problems, configurations, and effects will be clarified by the description of the embodiments below. [Brief explanation of the drawing]

[0017] [Figure 1] This diagram shows a schematic representation of the crystal lattice of diamond with nitrogen vacancy centers (NVCs), and an example of the detection of red fluorescence by optical magnetic resonance (ODMR). [Figure 2] This is a schematic diagram illustrating the basic concept of magnetic measurement using a diamond NVC sensor in the present invention. [Figure 3] This is a schematic diagram showing an example configuration of a magnetic property measuring device for soft magnetic materials according to the present invention. [Figure 4] This is an enlarged schematic diagram showing an example in which a thin-film diamond NVC sensor is positioned adjacent to / closely attached to the sample being measured. [Figure 5] This is an enlarged schematic diagram showing an example where a probe-shaped diamond NVC sensor is positioned adjacent to the sample being measured. [Figure 6] This is a schematic diagram showing an example of the display screen of the output device of a control and data analysis mechanism. [Figure 7] This flowchart shows an example of a magnetic properties measurement process using the measuring device of the present invention. [Figure 8] This flowchart shows another example of a magnetic properties measurement process using the measuring device of the present invention. [Figure 9] This is a schematic diagram showing an example of the results (magnetization curve and ODMR spectrum) of magnetic property measurements (magnetization curve and ODMR spectrum) performed on commercially available permalloy according to the present invention. [Figure 10] This is a schematic diagram showing an example of the results (magnetization curve and ODMR spectrum) of magnetic property measurements performed on commercially available Permendur according to the present invention. [Modes for carrying out the invention]

[0018] [Basic Concept of the Invention] First, we will briefly explain the magnetization curve (also called the MH curve or BH curve), which is fundamental to measuring magnetic properties. When an external magnetic field is applied to a magnetic sample that is in a non-magnetic state, the sample becomes magnetized. As the external magnetic field increases, the magnetization of the sample increases monotonically, but the magnetization of the sample saturates at a certain level. The magnetization at this point is called the saturation magnetization Ms, and the magnetic flux density is called the saturation magnetic flux density Bs.

[0019] As the external magnetic field is decreased from the saturation magnetization Ms, the magnetization of the sample also decreases monotonically, but often follows a different line than when the external magnetic field is increasing. This phenomenon is called hysteresis. Magnetic materials with large hysteresis are called hard magnets and are suitable for use as magnets. Magnetic materials with small hysteresis are called soft magnets and are suitable for use as iron cores. The hysteresis loss of iron loss Pi is proportional to the area of ​​the hysteresis curve, so from the viewpoint of iron loss Pi, the smaller the area of ​​the hysteresis curve, the more desirable (ideally, the curve has zero area).

[0020] Next, we will briefly explain magnetic measurement using a diamond NVC sensor.

[0021] Diamond NVCs are a type of lattice defect in which some carbon (C) atoms in a diamond crystal are replaced by nitrogen (N) atoms, resulting in vacancies adjacent to the N atoms due to the difference in valence states. Diamond NVCs have special properties that make them prone to trapping electrons and becoming negatively charged, and they can stably maintain their quantum spin state even at room temperature. See, for example, Non-Patent Document 1.

[0022] When a diamond NVC is irradiated with green laser light (wavelength 532 nm), it absorbs the energy, causing its spin to transition from the ground state to an excited state. Subsequently, it returns to its original ground state while emitting red fluorescence (wavelength 637 nm). When the amount of emitted red fluorescence is measured while irradiating with microwaves of various frequencies simultaneously with the green laser light, it is known that resonance occurs at a specific microwave frequency (2.87 GHz at 20°C), reducing the amount of detectable red fluorescence.

[0023] This phenomenon is called photodetector magnetic resonance (ODMR), and the minimum point of red fluorescence detection is called a dip. Figure 1 shows a schematic diagram of the crystal lattice of diamond with NVC, and a schematic diagram showing an example of red fluorescence detection by ODMR.

[0024] A dip occurs when the sample magnetic field acting on the diamond NVC (the leakage magnetic field emitted from the sample in response to the amount of magnetization of the sample) is zero, resulting in a single dip at a specific frequency (2.87 GHz at 20°C). However, when a sample magnetic field is applied to the diamond NVC (more precisely, in the direction parallel to the NV axis within the diamond crystal), it splits into two. This phenomenon is called Zeeman splitting. The magnitude of Zeeman splitting (the frequency difference from 2.87 GHz) is proportional to the magnitude of the sample magnetic field. This proportionality constant in Zeeman splitting is called the gyromagnetic ratio and is known to be 28 GHz / T. In other words, by precisely measuring the magnitude of Zeeman splitting (the frequency difference from 2.87 GHz), the sample magnetic field acting on the diamond NVC (in the direction parallel to the NV axis) can be precisely measured.

[0025] Furthermore, in a single-crystal diamond, the NV axis can take on four orientations due to its crystal structure. Therefore, a single-crystal diamond NVC sensor without any particular orientation of the NV axis will exhibit a total of four Zeeman splits (eight dips in total) corresponding to the magnitude of the sample magnetic field detected by each of the four NV axes. In other words, by precisely measuring the magnitude of these four Zeeman splits, the sample magnetic field acting on the single-crystal diamond NVC sensor can be analyzed three-dimensionally.

[0026] In this specification, for the sake of simplicity and to aid understanding, we will describe one Zeeman fission (two dips).

[0027] Conventional magnetization measurements using a diamond NVC sensor generally follow the following procedure. (1) Maintain and stabilize the sample magnetic field in a certain state. (2) Irradiate the diamond NVC sensor adjacent to the sample with green laser light. (3) While irradiating a diamond NVC sensor with green laser light, microwaves are irradiated and the frequency is swept to measure the amount of red fluorescence emitted from the diamond NVC sensor and to measure the microwave frequency at which a dip occurs. In other words, the frequency of the irradiated microwaves is swept until a dip is sufficiently observed. (4) Calculate the sample magnetic field value from the microwave frequency at which the dip occurs. (5) Change the sample magnetic field to the following state and return to (1). Of these steps, (3) takes the longest time. Furthermore, in order to precisely measure the magnetization curve, it is naturally desirable to minimize the change in the sample magnetic field during step (5).

[0028] For example, when measuring the magnetization of a soft magnetic sample in the range of "-20 mT ⇔ 20 mT" (a cycle of 0 mT → 20 mT → 0 mT → -20 mT → 0 mT → 20 mT) and in 1 mT increments, conventional magnetization measurements using a diamond NVC sensor require approximately 800 minutes in total, because the microwave sweep frequency width is set to cover the entire dip caused by Zeeman splitting at ±20 mT.

[0029] In contrast, magnetization measurements within the same range using VSM or the Epstein method take approximately 30 minutes. While conventional magnetization measurements using diamond NVC sensors offer an order of magnitude advantage in measurement accuracy, the length of the measurement time is considered unacceptable.

[0030] Therefore, the inventors diligently researched techniques for measuring magnetic properties using diamond NVC sensors in order to effectively utilize the highly attractive feature of diamond NVC sensors, which is their high measurement accuracy. As a result, they found that by effectively utilizing the high measurement accuracy, the frequency sweep width of the microwaves irradiated in step (3) can be greatly reduced, and the time required for measurement can be significantly shortened compared to conventional methods. The present invention was completed based on this finding.

[0031] Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the present invention is not limited to the specific embodiments described, and it is possible to combine it with or improve upon prior art without departing from the technical spirit of the invention.

[0032] (Principle of measuring the magnetic properties of soft magnetic materials in the present invention) In measuring magnetic properties, the magnetization of the sample being measured (sample magnetization) M smp [Unit: T] represents the permeability μ of the sample being measured. smp From [unit: T·m / A] and the external magnetic field (magnetic field applied to the sample being measured, also called magnetomotive force) H0 [unit: A / m], it can be expressed by the following equation (1). M smp = μ smp × H0...Equation (1).

[0033] As mentioned above, the sample magnetization M smp The leakage magnetic field emitted from the sample being measured is the sample magnetic field H. smp [Unit: A / m]. Sample magnetic field H smp In regions where diffusion attenuation does not occur (for example, near the surface of the sample), the sample magnetic field H smp Sample magnetization M smp The magnetic permeability μ0 [unit: T·m / A] of vacuum and the magnetic permeability of vacuum are related by the following equation (2). The magnetic property measurement method employed in the present invention involves placing a diamond NVC sensor near the surface of the sample to be measured and setting the sample magnetic field H smp It measures this. M smp = μ0 × H smp ...Equation (2).

[0034] Furthermore, since the magnetic property measurement method of the present invention is an ODMR measurement targeting soft magnetic materials, Zeeman splitting occurs as described above. The microwave frequency ω of the dip position due to this Zeeman splitting d [Unit: GHz] represents the gyromagnetic ratio of 28 [Unit: GHz / T], the permeability of vacuum μ0, and the sample magnetic field H smp Therefore, it can be expressed by the following equation (3). ω d = 2.87 ± 28 × μ0 × H smp ...Equation (3).

[0035] From equations (1) to (3), the following equation (4) holds true. ω d = 2.87 ± 28 × μ smp × H0...Equation (4).

[0036] This is the permeability μ of the sample being measured. smp If an approximate value is known, the diamond NVC sensor is placed adjacent to / close to the sample to measure the sample magnetic field H smp If the measurement is performed without diffusion attenuation, the microwave frequency ω at the dip position can be measured from the external magnetic field H0. d This means that we can estimate it to some extent.

[0037] Figure 2 is a schematic diagram illustrating the basic concept of magnetic measurement using a diamond NVC sensor in the present invention. As shown in Figure 2, the microwave frequency ω of the dip position in ODMR measurement d If we can estimate this to some extent, we can set the microwave frequency sweep width to ω d The neighboring region of (for example, ω d Even when limited to ±Δω (Δω = 0.01~0.05 GHz), the center frequency of the dip can be measured with high accuracy. In other words, the microwave sweep frequency can be set to ω for each sample magnetic field setting. d By limiting the measurement to only the immediate vicinity region, the measurement time can be significantly reduced compared to setting the frequency sweep width to cover the entire dip deviation due to Zeeman splitting.

[0038] In ODMR measurements, the dip position splits evenly between the positive and negative sides centered around a microwave frequency of 2.87 GHz (at 20°C) due to Zeeman splitting. Therefore, if prioritizing a reduction in measurement time, only one of the split sides may be measured. When the measurement time was estimated under the same conditions as before (in the range of "-20 mT ⇔ 20 mT", in 1 mT increments), it was found that the magnetization measurement method of the present invention reduces the measurement time from the conventional 800 minutes to approximately 28 minutes, which is equivalent to or less than that when performed by VSM or the Epstein method.

[0039] Furthermore, if prioritizing the measurement accuracy of the dip's center frequency (i.e., prioritizing the measurement accuracy of the sample magnetic field), it is desirable to measure both the positive and negative sides.

[0040] (Apparatus for measuring the magnetic properties of soft magnetic materials according to the present invention) Figure 3 is a schematic diagram showing an example of the configuration of a magnetic property measuring device for soft magnetic materials according to the present invention.

[0041] As shown in Figure 3, in the magnetic property measuring apparatus 100 for soft magnetic materials according to the present invention, the measurement sample 10 is placed in the sample setting mechanism 20, and a measurement sample magnetic field application mechanism 30 for applying a magnetic field to the measurement sample 10 is arranged around the measurement sample 10. The sample setting mechanism 20 is not particularly limited as long as it can stably set the measurement sample 10, and for example, an optical table 21 or a sample stage 22 can be suitably used. The measurement sample magnetic field application mechanism 30 is also not particularly limited as long as it can apply a magnetic field to the measurement sample 10, and for example, an electromagnet 31 or a power supply for applying a magnetic field 32 can be suitably used. A sample magnetic field 11 is generated on the measurement sample 10 by the magnetic field (external magnetic field 33) generated by the measurement sample magnetic field application mechanism 30. For the sake of simplifying the drawings and making them easier to understand, the sample magnetization and the sample magnetic field are collectively referred to as the sample magnetic field 11.

[0042] The diamond NVC sensor 40, which detects the sample magnetic field 11 of the measurement sample 10, is positioned adjacent to / closely in contact with the measurement sample 10. The diamond NVC sensor 40 is not particularly limited in shape, as long as it can efficiently detect the sample magnetic field 11 of the measurement sample 10. For example, it may be a thin film as taught in Non-Patent Document 2, or a probe as taught in Non-Patent Document 3. Figure 3 shows an example of a thin film diamond NVC sensor 40. The fact that there is no particular limitation on the shape of the diamond NVC sensor 40 leads to greater freedom in the shape of the measurement sample 10 (fewer constraints on the shape of the measurement sample 10).

[0043] Furthermore, the magnetic property measuring device 100 comprises, as a measurement system, a laser light irradiation mechanism 50 that irradiates the diamond NVC sensor 40 with green laser light (wavelength 532 nm), a microwave irradiation mechanism 60 that irradiates the diamond NVC sensor 40 with predetermined microwaves, and a photodetectable magnetic resonance spectrum measuring mechanism 70 that detects red fluorescence (wavelength 637 nm) from the diamond NVC sensor 40 and measures the photodetectable magnetic resonance spectrum.

[0044] The laser beam irradiation mechanism 50 illustrated in Figure 3 consists of a green laser source 51, an acousto-optic modulator (AOM) 52, a mirror 53, a half-mirror 54, an objective lens 55, etc., and the green laser beam 56 emitted from the green laser source 51 is irradiated onto the diamond NVC sensor 40. Although not an essential component, it is preferable to include a camera 57 so that the position of the diamond NVC sensor 40 and the position of the laser beam irradiation can be confirmed.

[0045] The microwave irradiation mechanism 60 consists of, for example, a microwave antenna 61 and a microwave generator 62. There are no particular limitations on the placement conditions of the microwave antenna 61 as long as it can efficiently irradiate the diamond NVC sensor 40 with microwaves 63, but it is preferable that it be placed within 100 mm of the diamond NVC sensor 40 (more precisely, from the magnetic characteristic measurement point).

[0046] The photodetection magnetic resonance spectroscopy measurement mechanism 70 consists of an objective lens 55, a half mirror 54, a mirror 53, a neutral density (ND) filter 71, a confocal pinhole 72, and an avalanche photodiode (APD) 73, and the amount of red fluorescence 74 emitted from the diamond NVC sensor 40 is detected by the APD 73.

[0047] Furthermore, the magnetic property measurement device 100 includes a control and data analysis mechanism 80 that controls the measurement sample magnetic field application mechanism 30, the laser light irradiation mechanism 50, and the microwave irradiation mechanism 60, and also analyzes data from the photodetection magnetic resonance spectrum measured by the photodetection magnetic resonance spectrum measurement mechanism 70. The control and data analysis mechanism 80 consists of a computer device (e.g., PC), input devices (e.g., keyboard, mouse, touchpad), output devices (e.g., display, printer), etc., and is interconnected with the measurement sample magnetic field application mechanism 30, the laser light irradiation mechanism 50, the microwave irradiation mechanism 60, and the photodetection magnetic resonance spectrum measurement mechanism 70.

[0048] Figure 4 is an enlarged schematic diagram showing an example in which a thin-film diamond NVC sensor is arranged adjacent to / closely in contact with the measurement sample. In the example shown in Figure 4, the diamond NVC sensor 40 has a structure in which a diamond NVC thin film 42 is arranged on a non-magnetic substrate 41 (for example, a glass substrate), and the entire sensor is arranged adjacent to / closely in contact with the measurement sample 10. A microwave antenna 61 connected to a connector 64 is also arranged on the diamond NVC sensor 40. Thin-film diamond NVC sensors have the advantage of being advantageous in terms of measurement accuracy.

[0049] Figure 5 is an enlarged schematic diagram showing an example in which a probe-shaped diamond NVC sensor is positioned adjacent to the measurement sample. In the example shown in Figure 5, the diamond NVC sensor 40' has a structure in which a diamond NVC probe 44 is positioned at the tip of a metal base 43 (for example, a tungsten base), and the diamond NVC probe 44 is positioned adjacent to the measurement sample 10. A microwave antenna 61' is also positioned near the diamond NVC sensor 40'. The probe-shaped diamond NVC sensor has the advantage of being advantageous for localized data acquisition in the magnetization of the measurement sample 10 (and thereby for acquiring two-dimensional and three-dimensional magnetization data of the measurement sample 10).

[0050] Figure 6 is a schematic diagram showing an example of the display screen of the output device of the control and data analysis mechanism. In the example shown in Figure 6, a menu bar 82 is located above the display screen 81, and various measurement menus are listed there. When one of the measurement menus is selected, various windows related to the selected measurement menu open below the menu bar 82.

[0051] For example, if magnetization curve measurement is selected as the measurement menu, the external magnetic field setting icon 83a, the measurement sample setting icon 83b, the laser light setting icon 83c, and the microwave setting icon 83d will appear on the left side of the display screen 81.

[0052] Clicking the external magnetic field setting icon 83a opens a window where you can input the range (upper and lower limits) of the external magnetic field 33 and the amount of change in the external magnetic field 33. Clicking the measurement sample setting icon 83b opens a window where you can input the permeability μ of the measurement sample 10. smp A window opens where you can input values ​​such as saturation magnetization Ms / saturation magnetic flux density Bs. Clicking the laser beam setting icon 83c opens a window where you can input the intensity of the green laser beam 56. Clicking the microwave setting icon 83d opens a window where you can input values ​​such as the microwave 63 intensity, sweep frequency width, frequency sweep speed, and number of measurement repetitions.

[0053] Once the external magnetic field settings, sample settings, laser light settings, and microwave settings (collectively referred to as "measurement conditions") are entered, the magnetization curve measurement start button 84a, stop button 84b, and red fluorescence detection amount display 85a become active. Clicking the start button 84a starts the magnetization curve measurement, and the magnetization curve display 85b and ODMR display 85c become active, allowing you to check the measurement status in real time. The measurement automatically ends when the set measurement sequence is completed, but you can interrupt the measurement by clicking the stop button 84b.

[0054] (Measurement process for magnetic properties using the measuring device of the present invention) Next, the process for measuring magnetic properties using the magnetic property measuring device 100 will be described.

[0055] Figure 7 is a flowchart showing an example of a magnetic properties measurement process using the measuring device of the present invention. As shown in Figure 7, first, a sample setting step S1 is performed in which the measurement sample 10 is placed in the sample setting mechanism 20. At this time, the measurement sample 10 may be placed in a location where the measurement sample magnetic field application mechanism 30 is already installed to correspond to the shape of the measurement sample 10 and the measurement sample magnetic field application mechanism 30, or the measurement sample magnetic field application mechanism 30 may be installed around the placed measurement sample 10 afterwards.

[0056] Next, a sensor placement step S2 is performed in which the diamond NVC sensor 40 is placed adjacent to / closely in contact with the measurement sample 10. At this time, the measurement sample 10 may be moved to a location where the diamond NVC sensor 40 has already been placed to match the shape of the measurement sample 10 and the diamond NVC sensor 40, or the diamond NVC sensor 40 may be placed on the measurement sample 10 after it has been installed.

[0057] Next, a measurement condition input step S3 is performed to input the measurement conditions for the magnetic properties of the measurement sample 10 to the control and data analysis mechanism 80. As mentioned above, the measurement conditions include the range and variation of the external magnetic field 33, and the permeability μ of the measurement sample 10. smp These include the intensity of the green laser light 56, the intensity, frequency sweep width, and frequency sweep speed of the microwave 63, and the number of repetitions of the magnetization curve measurement. Note that this step S3 does not necessarily have to be performed after step S2; the order does not matter as long as it is performed before the next magnetic property measurement step S4.

[0058] Next, in accordance with the measurement conditions in the measurement condition input step S3, an external magnetic field 33 is applied and controlled to the measurement sample 10, green laser light 56 ​​and microwaves 63 are irradiated and controlled to the diamond NVC sensor 40, and a magnetic property measurement step S4 is performed in which the dip of the ODMR is measured by measuring the light intensity of red fluorescence 74.

[0059] For example, if the frequency sweep width of microwave 63 is set to "Δω = 0.02 GHz", then in a 20°C environment, when the external magnetic field 33 is "H0 = 0 A / m", the dip in ODMR will be "ω d It should be observed at "ω = 2.87 GHz", so d The light intensity of the red fluorescence 74 should be measured within the range of "2.85 GHz ≤ ω ≤ 2.89 GHz" where ±Δω is the value. The frequency sweep width Δω of the microwave 63 is preferably 0.01 GHz or more and 0.05 GHz or less, and more preferably 0.015 GHz or more and 0.04 GHz or less.

[0060] Next, the control and data analysis mechanism 80 determines the center frequency of the dip from the shape of the dip obtained from the light intensity measurement data of the red fluorescence 74, and from this center frequency, it determines the sample magnetic field H0 at the external magnetic field H0 at that time. smp Perform data analysis step S5 to calculate the sample magnetic field H. smp The calculation can be performed using the relationship in equation (4) above. The sample magnetic field H in the external magnetic field H0 at that time smp Once the calculation is complete, return to characteristic measurement step S4 to perform the measurement under the next external magnetic field conditions.

[0061] Once all measurements set in the measurement condition input step S3 are complete, the analysis result output step S6 is performed to create and output the magnetization curve of the measurement sample 10. Note that the creation and output of the magnetization curve of the measurement sample 10 is not limited to when all measurements are complete; as mentioned above, it may be created and output as needed after each data analysis step S5.

[0062] Note that the dip position "ω" in ODMR measurement when the sample magnetic field is zero d The value "=2.87 GHz" is obtained under conditions of 20°C, and it is known that the dip position shifts by 0.00007 GHz for every 1°C change in ambient temperature. However, the shift due to ambient temperature is approximately 0.0024% / °C, which can usually be considered within the margin of error. On the other hand, it is also known that the dip position in ODMR measurements will shift from its original position if there is significant crystallographic strain in the diamond NVC sensor.

[0063] Therefore, a calibration step S0 (not shown) may be performed to confirm and calibrate the dip position deviation caused by ambient temperature and crystallographic distortion of the diamond NVC sensor. For example, the ambient temperature of the measurement and the dip position at zero sample magnetic field in the ODMR measurement may be accurately measured, and "ω d By measuring the difference from "=2.87 GHz", the deviation can be confirmed and calibrated. This step S0 is not a mandatory step and may be performed as needed. Alternatively, the sequence of step S0 may be incorporated into the control and data analysis mechanism 80 of the magnetic property measuring device 100.

[0064] (Another example of a magnetic properties measurement process using the measuring device of the present invention) Here, the permeability μ of the measurement sample 10 is found. smpThe following describes a case where the approximate value is not known in advance. Figure 8 is a flowchart showing another example of the magnetic properties measurement process using the measuring device of the present invention. As shown in Figure 8, the sample placement step S1 and the sensor placement step S2 are the same as the measurement process shown in Figure 7.

[0065] Next, the permeability μ of the measurement sample 10. smp The measurement condition partial input substep S3a is performed to input measurement conditions other than those specified. In other words, the permeability μ of the measurement sample 10. smp Other than the measurement conditions, the measurement process is the same as shown in Figure 7.

[0066] Next, based on the measurement conditions in the partial input of measurement conditions substep S3a, an ODMR spectral measurement is performed on the measurement sample 10 to determine the center frequency of the observed dip in the photodetection magnetic resonance spectral preliminary measurement substep S3b. As an example, at least one external magnetic field 33 is applied, selected from 20-80% of the range of the external magnetic field 33 input in the partial input of measurement conditions substep S3a, and the green laser light 56 ​​is irradiated at the intensity of the input green laser light 56. It is more preferable to select the external magnetic field 33 to be applied from 40-60% of the range of the external magnetic field 33 input in substep S3a.

[0067] Regarding the microwave 63, irradiation is performed at the intensity of the microwave 63 input in substep S3a, but frequency sweeping is performed until two dips in the ODMR are observed. Preferably, the sweeping speed at that time is 5 to 10 times the frequency sweeping speed input in substep S3a (high-speed sweep).

[0068] If the shapes of the two observed dips are relatively clear, the center frequencies of the dips are determined. On the other hand, if the shapes of the two observed dips are relatively unclear, a medium-speed sweep is performed at 2 to 4 times the input frequency sweep speed, limiting the sweep to the frequency domain of the observed dips (for example, limiting it to the range of 0.02 to 0.10 GHz to include the entire observed dip), and the center frequencies of the dips are determined.

[0069] Next, from the relationship between the applied external magnetic field 33, the determined dip center frequency, and the aforementioned equation (4), the permeability μ of the measurement sample 10 is calculated. smp The sample permeability calculation substep S3c is performed to calculate an approximate value of the permeability μ of the measurement sample 10. smp It is preferable that the measurement conditions are automatically written as such. This results in the same state as the measurement condition input step S3 shown in Figure 7.

[0070] The subsequent magnetic property measurement steps S4 to the analysis result output step S6 are the same as the measurement process shown in Figure 7. In other words, the measurement process shown in Figure 8 corresponds to dividing the measurement condition input step S3 in Figure 7 into the substeps S3a to S3c described above. [Examples]

[0071] The present invention will be described in more detail through actual measurements. However, the present invention is not limited to what is described below.

[0072] Figure 9 is a schematic diagram showing an example of the results (magnetization curve and ODMR spectrum) of magnetic property measurements performed on commercially available permalloy according to the present invention, and Figure 10 is a schematic diagram showing an example of the results (magnetization curve and ODMR spectrum) of magnetic property measurements performed on commercially available permendur according to the present invention. For the sake of simplicity in the drawings, hysteresis in the magnetization curve has been omitted.

[0073] The sample in Figure 9 is permalloy with a relative permeability of 180,000 and a saturation magnetic flux density of 0.72 T. Because of its relatively high permeability and relatively low Bs, the slope of the magnetization curve is steep, resulting in a small sample magnetic field. On the other hand, the sample in Figure 10 is permendur with a relative permeability of 10,000 and a saturation magnetic flux density of 2.45 T. Because of its relatively low permeability and relatively high Bs, the slope of the magnetization curve is gentle, resulting in a large sample magnetic field.

[0074] In all samples, when the external magnetic field is zero, there is a single dip in the ODMR spectrum at a microwave frequency of 2.87 GHz. However, as the external magnetic field is increased, Zeeman splitting becomes more pronounced, and the dip's divergence (frequency difference from 2.87 GHz) increases. Furthermore, the sample in Figure 10 (Permendur) has a higher Bs than the sample in Figure 9 (Permalloy), which means that a higher external magnetic field is required for measurement, resulting in a larger dip divergence.

[0075] Even with such samples, the magnetic property measurement according to the present invention is performed at the microwave frequency ω at the dip position of the ODMR spectrum. d We estimate the frequency sweep width of the microwaves and set ω d The neighboring region (ω d By limiting the measurement range to ±Δω (Δω = 0.01~0.05 GHz), the measurement time can be significantly reduced compared to conventional methods.

[0076] The embodiments described above are explained to aid in understanding the present invention, and the present invention is not limited to the specific configurations described. For example, it is possible to replace some of the configurations of the embodiments with configurations that are common knowledge to those skilled in the art, and it is also possible to add configurations that are common knowledge to those skilled in the art to the configurations of the embodiments. In other words, the present invention allows for deletion, substitution with other configurations, and addition of other configurations to some of the configurations of the embodiments specified herein, without departing from the technical spirit of the invention. [Explanation of symbols]

[0077] 100... Magnetic properties measuring device, 10...Measurement sample, 11...Sample magnetic field, 20...Sample setting mechanism, 21...Optical table, 22...Sample stage, 30...Mechanism for applying magnetic field to measurement sample, 31...Electromagnet, 32...Power supply for applying magnetic field, 33...External magnetic field, 40, 40'... Diamond NVC sensor, 41... Non-magnetic substrate, 42...Diamond NVC thin film, 43...Metal base, 44...Diamond NVC probe, 50...Laser light irradiation mechanism, 51...Green laser source, 52...Acousto-optic modulator, 53...Mirror, 54... Half mirror, 55... Objective lens, 56... Green laser light, 57... Camera, 60...Microwave irradiation mechanism, 61, 61'...Microwave antenna, 62...Microwave generator, 63...Microwave, 64...Connector 70... Photodetector magnetic resonance spectroscopy mechanism, 71... Neutral density filter, 72...Confocal pinhole, 73...Avalanche photodiode, 74...Red fluorescence, 80...Control and data analysis mechanism, 81...Display screen, 82...Menu bar, 83a…External magnetic field setting icon, 83b…Measurement sample setting icon, 83c... Laser beam setting icon, 83d... Microwave setting icon, 84a... Start button, 84b... Stop button, 85a...Detection amount display, 85b...Magnification curve display, 85c...ODMR display.

Claims

1. A method for measuring the magnetic properties of a soft magnetic material using a diamond NVC sensor, A measurement condition input step for inputting the measurement conditions for the magnetic properties, A magnetic property measurement step in which, in accordance with the above measurement conditions, an external magnetic field is applied to the measurement sample of the soft magnetic material, and the diamond NVC sensor disposed on the measurement sample is irradiated with green laser light and microwaves in a predetermined frequency range, and the dip in the photodetectable magnetic resonance spectrum is measured by detecting red fluorescence from the diamond NVC sensor. The system includes a data analysis step of determining the center frequency of the dip and calculating the magnetic field of the measurement sample in the external magnetic field from the center frequency, The measurement conditions are as follows: the external magnetic field H 0 [Unit: A / m] Range, permeability μ of the measurement sample smp [Unit: T・m / A] and a predetermined frequency sweep width Δω in the microwave, The predetermined frequency range of the microwave in the magnetic property measurement step is In a 20℃ environment, "ω d = 2.87 ± 28 × μ smp × H 0 The microwave frequency ω of the dip can be determined from the relationship ''. d [Unit: GHz] based on "ω d This is the region ±Δω. A method for measuring the magnetic properties of a soft magnetic material, characterized by the features described herein.

2. In the method for measuring the magnetic properties of a soft magnetic material according to claim 1, The aforementioned measurement condition input step is Permeability μ of the aforementioned measurement sample smp A substep for inputting measurement conditions other than those specified, Based on the measurement conditions in the aforementioned measurement condition partial input substep, the external magnetic field is applied to the measurement sample, and while irradiating the diamond NVC sensor with the green laser light and the microwave, the dip in the photodetectable magnetic resonance spectrum is measured and the center frequency of the dip is determined in the photodetectable magnetic resonance spectrum preliminary measurement substep. From the applied external magnetic field, the center frequency of the obtained dip, and the relational expression, the magnetic permeability μ of the measurement sample smp a sample magnetic permeability calculation sub-step for calculating; A method for measuring the magnetic properties of a soft magnetic material, characterized by being divided and executed in stages.

3. In the method for measuring the magnetic properties of a soft magnetic material according to claim 2, The measurement conditions further include the frequency sweep rate of the microwave, The external magnetic field in the photodetection magnetic resonance spectrum preliminary measurement substep is at least one magnetic field selected from 20% to 80% of the range of the external magnetic field input in the measurement condition partial input substep. In the photodetection magnetic resonance spectrum preliminary measurement substep, the microwave irradiation is performed at a speed of 5 to 10 times the frequency sweep speed input in the measurement condition partial input substep. A method for measuring the magnetic properties of a soft magnetic material, characterized by the features described herein.

4. In the method for measuring the magnetic properties of a soft magnetic material according to claim 1, A method for measuring the magnetic properties of a soft magnetic material, characterized in that the magnetic property measurement step is performed only on "the region on the side of less than 2.87 GHz" or "the region on the side of greater than 2.87 GHz" of the Zeeman-split dip.

5. In the method for measuring the magnetic properties of a soft magnetic material according to claim 2, A method for measuring the magnetic properties of a soft magnetic material, characterized in that the magnetic property measurement step is performed only on "the region on the side of less than 2.87 GHz" or "the region on the side of greater than 2.87 GHz" of the Zeeman-split dip.

6. In the method for measuring the magnetic properties of a soft magnetic material according to claim 3, A method for measuring the magnetic properties of a soft magnetic material, characterized in that the magnetic property measurement step is performed only on "the region on the side of less than 2.87 GHz" or "the region on the side of greater than 2.87 GHz" of the Zeeman-split dip.

7. In a method for measuring the magnetic properties of a soft magnetic material according to any one of claims 1 to 6, A method for measuring the magnetic properties of a soft magnetic material, characterized in that the predetermined frequency sweep width Δω is 0.01 GHz or more and 0.05 GHz or less.

8. A device for measuring the magnetic properties of soft magnetic materials, A sample setting mechanism for setting the soft magnetic material that will be used as a measurement sample, A measurement sample magnetic field application mechanism for applying an external magnetic field to the measurement sample, A diamond NVC sensor for detecting the magnetic field of the sample being measured, A laser beam irradiation mechanism that irradiates the diamond NVC sensor with green laser light, A microwave irradiation mechanism that irradiates the diamond NVC sensor with predetermined microwaves, A photodetectable magnetic resonance spectrum measurement mechanism that detects red fluorescence from the diamond NVC sensor and measures the photodetectable magnetic resonance spectrum, The system includes a control and data analysis mechanism that controls the measurement sample magnetic field application mechanism, the laser light irradiation mechanism, and the microwave irradiation mechanism, and also analyzes data from the photodetectable magnetic resonance spectrum measured by the photodetectable magnetic resonance spectrum measurement mechanism, The aforementioned control and data analysis mechanism is: A measurement condition input step for inputting the measurement conditions for the magnetic properties, A magnetic property measurement step in which the external magnetic field is applied to and controlled on the measurement sample in accordance with the measurement conditions, the green laser light and microwaves are irradiated and controlled on the diamond NVC sensor, and the dip in the photodetectable magnetic resonance spectrum due to red fluorescence from the diamond NVC sensor is measured. A data analysis step which involves determining the center frequency of the dip and calculating the magnetic field of the measurement sample in the external magnetic field from the center frequency, It is configured to perform the following actions: The measurement conditions are as follows: the external magnetic field H 0 [Unit: A / m] Range, permeability μ of the measurement sample smp [Unit: T・m / A] and a predetermined frequency sweep width Δω in the microwave, The predetermined frequency range of the microwave in the magnetic property measurement step is In a 20℃ environment, "ω d = 2.87 ± 28 × μ smp × H 0 The microwave frequency ω of the dip can be determined from the relationship ''. d [Unit: GHz] based on "ω d This is the region ±Δω. A device for measuring the magnetic properties of soft magnetic materials, characterized by the following features.

9. In the magnetic properties measuring apparatus for a soft magnetic material according to claim 8, The aforementioned measurement condition input step is Permeability μ of the aforementioned measurement sample smp A substep for inputting measurement conditions other than those specified, Based on the measurement conditions in the aforementioned measurement condition partial input substep, the external magnetic field is applied to the measurement sample, and while irradiating the diamond NVC sensor with the green laser light and the microwave, the dip in the photodetectable magnetic resonance spectrum is measured and the center frequency of the dip is determined in the photodetectable magnetic resonance spectrum preliminary measurement substep. From the applied external magnetic field, the center frequency of the dip determined, and the relational equation, the permeability μ of the measurement sample is obtained. smp A substep for calculating the sample permeability, A device for measuring the magnetic properties of a soft magnetic material, characterized by being divided and executed in stages.

10. In the magnetic properties measuring apparatus for a soft magnetic material according to claim 9, The measurement conditions further include the frequency sweep rate of the microwave, The external magnetic field in the photodetection magnetic resonance spectrum preliminary measurement substep is at least one magnetic field selected from 20% to 80% of the range of the external magnetic field input in the measurement condition partial input substep. In the photodetection magnetic resonance spectrum preliminary measurement substep, the microwave irradiation is performed at a speed of 5 to 10 times the frequency sweep speed input in the measurement condition partial input substep. A device for measuring the magnetic properties of soft magnetic materials, characterized by the following features.

11. In the magnetic properties measuring apparatus for a soft magnetic material according to claim 8, A magnetic property measurement device for a soft magnetic material, characterized in that the magnetic property measurement step is performed only on "the region on the side of less than 2.87 GHz" or "the region on the side of greater than 2.87 GHz" of the Zeeman-split dip.

12. In the magnetic properties measuring apparatus for a soft magnetic material according to claim 9, A magnetic property measurement device for a soft magnetic material, characterized in that the magnetic property measurement step is performed only on "the region on the side of less than 2.87 GHz" or "the region on the side of greater than 2.87 GHz" of the Zeeman-split dip.

13. In the magnetic properties measuring apparatus for a soft magnetic material according to claim 10, A magnetic property measurement device for a soft magnetic material, characterized in that the magnetic property measurement step is performed only on "the region on the side of less than 2.87 GHz" or "the region on the side of greater than 2.87 GHz" of the Zeeman-split dip.

14. In the magnetic properties measuring apparatus for a soft magnetic material according to any one of claims 8 to 13, A magnetic properties measuring device for soft magnetic materials, characterized in that the predetermined frequency sweep width Δω is 0.01 GHz or more and 0.05 GHz or less.

Images