Method for measuring magnetic moment of transition metal material based on XPS

Abstract

The invention provides a method for measuring the magnetic moment of a transition metal material based on XPS, and the method comprises the steps: selecting a to-be-tested material single crystal, and transferring a single crystal sample into an X-ray photoelectron spectrometer; selecting an X-ray source; setting a test point position, and setting scanning parameters including energy passing, scanning step length, beam spot size and a magnetic lens mode; selecting a peak value of a 2p orbit high-resolution narrow spectrum corresponding to the transition metal contained in the to-be-detected sample as a fixed-height reference signal, and etching the surface of the sample to remove surface pollution; determining the position of a 3s orbit characteristic peak according to a broad spectrum, and collecting a 3s orbit high-resolution narrow spectrum of transition metal contained in the sample; collecting a valence band spectrum or a C1s orbit high-resolution narrow spectrum for correcting a broad spectrum and a 3s orbit high-resolution narrow spectrum; correcting the binding energy by adopting a correction reference, carrying out peak-dividing fitting through XPS peak-dividing fitting software, and extracting characteristic parameters of a 3s orbit spin exchange split peak; and calculating to obtain the magnetic moment of the transition metal material.

Description

Technical Field

[0001] This invention belongs to the field of transition metal material performance characterization technology, specifically relating to a method for measuring the magnetic moment of transition metal materials based on XPS. Background Technology

[0002] The 3d orbital spin intensity of transition metal materials is a key parameter determining their core properties such as magnetism, catalytic activity, and conductivity, and has significant application value in fields such as new energy batteries, catalytic reactions, and magnetic devices. Accurate measurement of 3d orbital spin intensity is crucial for optimizing material performance and expanding applications. Existing methods for measuring 3d orbital spin intensity mainly include magnetic measurement, neutron diffraction, and electron paramagnetic resonance (EPR). Magnetic measurement is easily affected by sample morphology and impurities, resulting in limited measurement accuracy; neutron diffraction equipment is expensive, has a long testing cycle, and requires stringent sample size and purity; EPR is only applicable to paramagnetic materials with unpaired electrons, limiting its applicability. X-ray photoelectron spectroscopy (XPS) offers advantages such as minimal sample damage, fast analysis speed, and high surface sensitivity. Significant spin exchange occurs between 3s orbital electrons and unpaired 3d orbital electrons in transition metals, leading to characteristic splitting of the 3s orbital photoelectron spectral peaks. The splitting parameters (peak spacing, peak area ratio) have a clear quantitative correlation with the 3d orbital spin intensity. However, there is currently no standardized method for rapidly and accurately measuring the 3D orbital spin intensity and magnetic moment of transition metals based on XPS technology and combined with XPS peak fitting software, and this technological gap urgently needs to be filled. Summary of the Invention

[0003] The purpose of this invention is to provide a method for measuring the magnetic moment of transition metal materials based on XPS. By utilizing the spin exchange and splitting characteristics of the 3s orbitals of transition metals and combining the data processing function of XPS peak fitting software, a rapid and accurate measurement of the 3d orbital spin intensity can be achieved.

[0004] Technical Solution: To achieve the above-mentioned objectives, this invention proposes a method for measuring the magnetic moment of transition metal materials based on XPS, wherein the transition metal is any one of Cr, Mn, Fe, Co, and Ni. The method includes the following steps:

[0005] Sample preparation: Select a single crystal of the material to be tested, and transfer the single crystal sample to the X-ray photoelectron spectrometer by bonding it to the sample holder with conductive adhesive.

[0006] Instrument parameter settings: Select X-ray source; Set test point; Set scanning parameters, including power, scanning step size, beam size, and magnetic lens mode;

[0007] Data acquisition involves selecting the peak value of the 2p orbital high-resolution narrow spectrum corresponding to the transition metal contained in the sample as a height reference signal, and etching the sample surface to remove surface contamination. Broad spectrum acquisition involves confirming the position of the 3s orbital characteristic peak based on the broad spectrum and acquiring the 3s orbital high-resolution narrow spectrum of the transition metal contained in the sample. Subsequently, valence band spectrum or C1s orbital high-resolution narrow spectrum is acquired to correct the broad spectrum and the 3s orbital high-resolution narrow spectrum of the transition metal contained in the sample.

[0008] Data processing and analysis involved correcting the binding energy using a calibration benchmark, performing peak fitting using XPS peak fitting software, and extracting characteristic parameters of the 3s orbital spin exchange splitting peak. Based on the correlation between the characteristic parameters and the magnitude of the magnetic moment, the magnitude of the magnetic moment of the transition metal material was calculated.

[0009] Furthermore, the sample preparation specifically includes:

[0010] Wipe the sample holder with ethanol, and attach a piece of conductive adhesive the same size as the sample to the sample holder; then clamp the selected transition metal single crystal sample onto the conductive adhesive of the sample holder.

[0011] The sample holder is transferred to the pretreatment chamber, which is then evacuated until it reaches the set vacuum level of 1*10. -8 Then, the sample tray is transferred to the X-ray photoelectron spectroscopy analysis chamber.

[0012] Furthermore, in the instrument parameter settings, the AlKα monochromatic source was selected as the X-ray source, with a radiation energy of 1486.6 eV.

[0013] Furthermore, during data acquisition, a single-atom etching mode was selected, with a kinetic energy of 2000 eV and an etching time of 30 seconds.

[0014] Furthermore, in data collection:

[0015] The valence band spectrum scanning range is 0 eV-50 eV, the pass energy is 20-50 eV, the scanning step size is 0.05-0.1 eV, the number of scans is 5-20, and the beam spot size is 100-800 μm.

[0016] The high-resolution narrow-spectrum C1s scanning range is 280 eV-295 eV, the pass energy is 30-50 eV, the scan step size is 0.05-0.1 eV, the number of scans is 3-5, and the beam spot size is 100-800 μm.

[0017] The wide-spectrum scanning range is 0-1300eV, the pass energy is 100-150eV, the number of scans is 1-2, and the beam spot size is 100-800μm.

[0018] The high-resolution narrow spectrum acquisition range of the 3s orbitals corresponding to the transition metals contained in the sample is 50-150 eV, the pass energy is 20-35 eV, the scan step size is 0.05-0.1 eV, the number of scans is 5-25, and the beam spot size is 100-800 μm.

[0019] Furthermore, the characteristic parameter of the 3s orbital spin exchange splitting peak is the exchange splitting peak spacing ΔE.

[0020] Furthermore, the data processing and analysis specifically include:

[0021] Charge correction: C1s is used as the correction reference for correction of the broad spectrum and the high-resolution narrow spectrum of the 3s orbitals of the transition metals contained in the sample. The correction reference binding energy is 284.8±0.1eV. Alternatively, valence band spectral calibration can be used to calibrate the binding energy of the Fermi level to 0±0.1eV.

[0022] Background subtraction: Select smart background and subtract inelastic scattering electron contributions;

[0023] Peak fitting: Peak fitting was performed using XPS peak fitting software. The peak shape parameters were set as follows: Gaussian-Lorentz mixture ratio of 65-75% Gaussian and 25-35% Lorentz, and full width at half maximum (FWHM) of 1-3.5 eV.

[0024] Parameter extraction: Extract the peak position values ​​of the two characteristic peaks formed by the spin exchange splitting of the 3s orbital, and calculate the peak spacing ΔE;

[0025] Further, the spin intensity is calculated as follows: Based on the pre-defined correlation formula ΔE=[(2S+1) / S]G2(3s,3d), where G2(3s,3d) is the exchange intensity coefficient, the 3d orbital spin intensity S is calculated by substituting it into ΔE after calibration with a standard transition metal sample. Based on the quantum expression of angular momentum μ=[S(S+1)]1 / 2, where μ represents the magnetic moment, since the parameter G2(3s,3d) is an electron interaction, it is considered constant in different samples, and is simplified to ΔE =k*μ+b, where k and b are the fitting parameters.

[0026] Furthermore, the fitting parameters k and b are calibrated as follows: select two or more standard transition metal samples with known 3d orbital spin intensities, measure their 3s orbital splitting peak parameters ΔE, establish a correlation formula through linear fitting, and determine the values ​​of k and b.

[0027] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0028] This invention utilizes the characteristic peak splitting phenomenon caused by the spin exchange between the 3s and 3d orbitals of transition metals. Combined with the precise data processing capabilities of the XPS peak fitting software Avantage, a quantitative correlation between the splitting parameters and the spin intensity of the 3d orbitals is established, enabling rapid and low-damage measurement of spin intensity. The measurement process is simple to operate and has low sample requirements, making it applicable to a variety of transition metal elements and compound materials. It effectively compensates for the shortcomings of existing measurement methods and meets the characterization needs in materials research and development and industrial applications. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating the execution process of the measurement method of the present invention;

[0030] Figure 2 This is a high-resolution narrow spectrum XPS image of the 3s orbitals of the Mn-based material under test (including peak fitting results);

[0031] Figure 3 This is a linear fitting curve of the calibration coefficient k. Detailed Implementation

[0032] To better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] It should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used solely for the convenience of describing these embodiments and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature.

[0034] First, the core principle of this invention is explained: There is a spin exchange interaction between the 3s orbital electrons and the unpaired electrons in the 3d orbitals of transition metal atoms. This interaction causes the XPS characteristic peak of the 3s orbital to split into two split peaks with a specific spacing and area ratio. The spacing (ΔE) of the split peaks increases with the number of unpaired electrons in the 3d orbital and is related to the orientation of the 3d orbital spin magnetic moment. Both of these factors together form a quantitative correlation with the magnitude of the magnetic moment, which is the theoretical basis of the measurement method of this invention.

[0035] Please refer to Figure 1 to Figure 3 As shown, this invention proposes a method for measuring the magnetic moment of transition metal materials based on XPS, wherein the transition metal is any one of Cr, Mn, Fe, Co, and Ni. The method includes the following steps:

[0036] Sample preparation: Select a single crystal of the material to be tested, and transfer the single crystal sample to the X-ray photoelectron spectrometer by bonding it to the sample holder with conductive adhesive.

[0037] Instrument parameter settings: Select X-ray source; Set test point; Set scanning parameters, including power, scanning step size, beam size, and magnetic lens mode;

[0038] Data acquisition involves selecting the peak value of the 2p orbital high-resolution narrow spectrum corresponding to the transition metal contained in the sample as a height reference signal, and etching the sample surface to remove surface contamination. Broad spectrum acquisition involves confirming the position of the 3s orbital characteristic peak based on the broad spectrum and acquiring the 3s orbital high-resolution narrow spectrum of the transition metal contained in the sample. Subsequently, valence band spectrum or C1s orbital high-resolution narrow spectrum is acquired to correct the broad spectrum and the 3s orbital high-resolution narrow spectrum of the transition metal contained in the sample.

[0039] Data processing and analysis involved correcting the binding energy using a calibration benchmark, performing peak fitting using XPS peak fitting software, and extracting characteristic parameters of the 3s orbital spin exchange splitting peak. Based on the correlation between the characteristic parameters and the magnitude of the magnetic moment, the magnitude of the magnetic moment of the transition metal material was calculated.

[0040] In a preferred embodiment of the present invention, the sample preparation specifically includes:

[0041] Wipe the sample holder with ethanol, and attach a piece of conductive adhesive the same size as the sample to the sample holder; then clamp the selected transition metal single crystal sample onto the conductive adhesive of the sample holder.

[0042] The sample holder is transferred to the pretreatment chamber, which is then evacuated until it reaches the set vacuum level of 1*10. -8 Then, the sample tray is transferred to the X-ray photoelectron spectroscopy analysis chamber.

[0043] In a preferred embodiment of the present invention, in the instrument parameter settings, the AlKα monochromatic source is selected as the X-ray source with an energy of 1486.6 eV to avoid interference peaks from other X-ray sources affecting the 3s orbit analysis.

[0044] In a preferred embodiment of the present invention, when acquiring data, an appropriate power level is set to balance measurement resolution and signal intensity; an appropriate scan step size is set to ensure accurate capture of peak details; and a beam spot size is set to reduce X-ray irradiation damage to the sample.

[0045] In a preferred embodiment of the present invention, during the data acquisition:

[0046] The valence band spectrum scanning range is 0 eV-50 eV, the pass energy is 20-50 eV, the scanning step size is 0.05-0.1 eV, the number of scans is 5-20, and the beam spot size is 100-800 μm.

[0047] The C1s high-resolution narrow-spectrum scanning range is 280 eV-295 eV, the pass energy is 30-50 eV, the scan step size is 0.05-0.1 eV, the number of scans is 3-5, and the beam spot size is 100-800 μm.

[0048] The wide-spectrum scanning range is 0-1300 eV, the pass energy is 100-150 eV, the number of scans is 1-2, and the beam spot size is 100-800 μm.

[0049] The high-resolution narrow spectrum acquisition range for the 3s orbitals of the transition metals contained in the sample is 50-150 eV (e.g., 74-96 eV for Mn samples), with a pass energy of 20-35 eV, a scan step size of 0.05-0.1 eV, 5-25 scans, and a beam size of 100-800 μm.

[0050] In a preferred embodiment of the present invention, the characteristic parameters of the 3s orbital spin exchange splitting peak include the splitting peak spacing ΔE, where ΔE is the peak position difference between the two splitting peaks (unit: eV).

[0051] In a preferred embodiment of the present invention, the data processing and analysis specifically include:

[0052] Charge correction: C1s is used as the correction reference for correction of the broad spectrum and the high-resolution narrow spectrum of the 3s orbitals of the transition metals contained in the sample. The correction reference binding energy is 284.8±0.1eV. Alternatively, valence band spectral calibration can be used to calibrate the binding energy of the Fermi level to 0±0.1eV.

[0053] Background subtraction: Select smart background and subtract inelastic scattering electron contributions;

[0054] Peak fitting: Peak fitting was performed using XPS peak fitting software. The peak shape parameters were set as follows: Gaussian-Lorentz mixture ratio of 65-75% Gaussian and 25-35% Lorentz, and full width at half maximum (FWHM) of 1-3.5 eV.

[0055] Parameter extraction: Extract the peak position values ​​of the two characteristic peaks formed by the spin exchange split of the 3s orbital and calculate the peak spacing ΔE.

[0056] Magnetic moment calculation: based on the preset correlation formula ΔE=[(2S+1) / S]G2 (3s,3d), where G 2 (3s, 3d) represents the exchange intensity coefficient, calibrated using a standard transition metal sample. Substituting this coefficient into ΔE yields the 3d orbital spin intensity S, which is expressed as μ = [S(S+1)] based on the magnitude of angular momentum. 1 / 2 Where μ represents the magnitude of the magnetic moment, and S is the calculated 3d orbital spin intensity, due to the parameter G 2 (3s,3d) is an electronic interaction that remains almost unchanged across different samples and can be approximated as ΔE=k*μ+b, where k and b are the fitting parameters.

[0057] In a preferred embodiment of the present invention, the calibration coefficient k is calibrated as follows: Select two or more standard transition metal samples with known 3d orbital spin intensities (such as MnO (known ΔE=6.0eV, μ=5.92μB / atom) and Mn2O3 (known ΔE=5.3eV, μ=4.90μB / atom), and measure the 3s orbital splitting peak parameter ΔE of each standard sample using this method to obtain multiple sets of (μ, ΔE) data; with μ as the dependent variable and ΔE as the independent variable, establish the correlation formula ΔE=k*μ+b through linear fitting, and determine the specific values ​​of k and b. The specific values ​​need to be adjusted according to the actual situation of the instrument and the standard samples.

[0058] The technical solution of the present invention will be further described in detail below through specific test examples:

[0059] This invention sets up two sets of standard samples and one set of test samples for experimental setup:

[0060] Standard sample 1: MnO standard sample (known magnetic moment μ = 5.92 μB / atom), ΔE = 6.0 eV;

[0061] Standard sample 2: Mn2O3 standard sample (known magnetic moment μ = 4.90 μB / atom), ΔE = 5.3 eV;

[0062] Substituting the above data into the correlation formula ΔE = k*μ+b, the calibration coefficients k = 0.392 and b = 3.578 were obtained through linear fitting.

[0063] The sample to be tested was MnTe2 material. The 3s orbital splitting peak ΔE = 5.07 eV was obtained by this method. Substituting into the correlation formula, we can calculate: ΔE = 0.392*μ+3.578 ≈ 5.07 eV, that is, the magnetic moment of MnTe2 material is 3.81 μB / atom.

[0064] The above test results show that the present invention can accurately calculate the 3d orbital spin intensity by measuring the 3s orbital spin exchange splitting parameters of transition metals using XPS, combined with data processing and calibration formulas from Avantage software, with a measurement error ≤ ±10%, meeting the accuracy requirements for material characterization.

[0065] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for measuring the magnetic moment of a transition metal material based on XPS, wherein the transition metal is any one of Cr, Mn, Fe, Co, and Ni, characterized in that... The method includes the following steps: Sample preparation: Select a single crystal of the material to be tested, and attach the single crystal sample to the sample holder with conductive adhesive, then transfer it into the X-ray photoelectron spectrometer. Instrument parameter settings: Select X-ray source; Set the test points, set the scanning parameters, including power, scanning step size and beam size, and magnetic lens mode; Data acquisition involves selecting the peak value of the 2p orbital high-resolution narrow spectrum corresponding to the transition metal contained in the sample as a height reference signal, and etching the sample surface to remove surface contamination; broad spectrum acquisition involves confirming the position of the 3s orbital characteristic peak based on the broad spectrum, and acquiring the 3s orbital high-resolution narrow spectrum of the transition metal contained in the sample; valence band spectrum or C1s orbital high-resolution narrow spectrum is acquired to correct the broad spectrum and the 3s orbital high-resolution narrow spectrum of the transition metal contained in the sample. Data processing and analysis involved correcting the binding energy using a calibration benchmark, performing peak fitting using XPS peak fitting software, and extracting characteristic parameters of the 3s orbital spin exchange splitting peak. Based on the correlation between the characteristic parameters and the magnitude of the magnetic moment, the magnitude of the magnetic moment of the transition metal material was calculated.

2. The method for measuring the magnetic moment of transition metal materials based on XPS according to claim 1, characterized in that, The sample preparation specifically includes: Wipe the sample holder with ethanol, and attach a piece of conductive adhesive the same size as the sample to the sample holder; then clamp the selected transition metal single crystal sample onto the conductive adhesive of the sample holder. The sample holder is transferred to the pretreatment chamber, which is then evacuated until it reaches the set vacuum level of 1*10. -8 Then, the sample tray is transferred to the X-ray photoelectron spectroscopy analysis chamber.

3. The method for measuring the magnetic moment of transition metal materials based on XPS according to claim 1, characterized in that, In the instrument parameter settings, the AlKα monochromatic source was selected as the X-ray source, and the radiation energy was 1486.6 eV.

4. The method for measuring the magnetic moment of transition metal materials based on XPS according to claim 1, characterized in that, During data acquisition, the etching mode was selected as single-atom etching, with a kinetic energy of 2000eV and an etching time of 30 seconds.

5. The method for measuring the magnetic moment of transition metal materials based on XPS according to claim 1, characterized in that, During data acquisition: The valence band spectrum scanning range is 0 eV-50 eV, the pass energy is 20-50 eV, the scanning step size is 0.05-0.1 eV, the number of scans is 5-20, and the beam spot size is 100-800 μm. The high-resolution narrow-spectrum C1s scanning range is 280 eV-295 eV, the pass energy is 30-50 eV, the scanning step size is 0.05-0.1 eV, the number of scans is 3-5, and the beam spot size is 100-800 μm. The wide-spectrum scanning range is 0-1300eV, the pass energy is 100-150eV, the number of scans is 1-2, and the beam spot size is 100-800μm. The high-resolution narrow spectrum acquisition range of the 3s orbitals corresponding to the transition metals contained in the sample is 50-150 eV, the pass energy is 20-35 eV, the scan step size is 0.05-0.1 eV, the number of scans is 5-25, and the beam spot size is 100-800 μm.

6. The method for measuring the magnetic moment of transition metal materials based on XPS according to claim 1, characterized in that, The characteristic parameter of the 3s orbital spin exchange splitting peak is the exchange splitting peak spacing ΔE.

7. The method for measuring the magnetic moment of transition metal materials based on XPS according to claim 1, characterized in that, The data processing and analysis specifically include: Charge correction: C1s is used as the correction reference for correction of the broad spectrum and the high-resolution narrow spectrum of the 3s orbitals of the transition metals contained in the sample. The correction reference binding energy is 284.8±0.1eV. Alternatively, valence band spectral calibration can be used to calibrate the binding energy of the Fermi level to 0±0.1eV. Background subtraction: Select smart background and subtract inelastic scattering electron contributions; Peak fitting: Peak fitting was performed using XPS peak fitting software. The peak shape parameters were set as follows: Gaussian-Lorentz mixture ratio of 65-75% Gaussian and 25-35% Lorentz, and full width at half maximum (FWHM) of 1-3.5 eV. Parameter extraction: Extract the peak position values ​​of the two characteristic peaks formed by the spin exchange split of the 3s orbital and calculate the peak spacing ΔE.

8. The method for measuring the magnetic moment of transition metal materials based on XPS according to claim 1, characterized in that, Spin intensity calculation: based on the pre-defined correlation formula ΔE=[(2S+1) / S]G 2 (3s,3d), where G 2 (3s, 3d) represents the exchange intensity coefficient, calibrated using a standard transition metal sample. Substituting this coefficient into ΔE yields the 3d orbital spin intensity S, which is expressed as μ = [S(S+1)] based on the magnitude of angular momentum. 1 / 2 Where μ represents the magnitude of the magnetic moment, due to the parameter G 2 (3s,3d) is the electron interaction, which is considered constant in different samples and can be simplified to ΔE=k*μ+b, where k and b are the fitting parameters.

9. The method for measuring the magnetic moment of a transition metal material based on XPS according to claim 8, characterized in that, The fitting parameters k and b are calibrated as follows: select two or more standard transition metal samples with known 3d orbital spin intensities, measure their 3s orbital splitting peak parameters ΔE, establish a correlation formula through linear fitting, and determine the values ​​of k and b.

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