Ferromagnetic resonance line width automatic test system and method thereof

Abstract

The invention relates to the technical field of material physical property testing, in particular to a ferromagnetic resonance linewidth automatic testing system and method, and the system comprises a main control unit, a signal generator, a spectrum analyzer, a magnetic field generation device, a gauss meter, a microwave transmission structure and two attenuators. The signal generator, the spectrum analyzer, the magnetic field generation device and the gauss meter are electrically connected with the main control unit, one attenuator is connected between the signal generator and the microwave transmission structure, the other attenuator is connected between the microwave transmission structure and the spectrum analyzer, and a crystal oscillator synchronization line is connected between the spectrum analyzer and the signal generator. The method comprises the following steps of: scanning point by point to read the readings of a spectrum analyzer influenced by a sample under different frequencies and different magnetic field intensities, and performing data curve fitting according to three groups of data of the frequency, the magnetic field intensity and the power to obtain a ferromagnetic resonance line width result of the sample; the signal generator and the spectrum analyzer are cheaper than the network analyzer.

Description

Technical Field

[0001] The present invention relates to the technical field of testing the physical properties of materials, and in particular to an automatic test system and method for ferromagnetic resonance linewidth. Background Art

[0002] Ferromagnetic resonance refers to the phenomenon that when a ferromagnetic sample is simultaneously placed in a microwave field and a steady magnetic field that are perpendicular to each other, and when the frequency of the microwave field is the same as the precession frequency of the magnetic moment of the ferromagnetic in a specific steady magnetic field, the ferromagnetic generates resonance, and thus the energy absorbed in the microwave field reaches a maximum value. Currently, the mainstream method for ferromagnetic resonance linewidth uses a network analyzer as the key test instrument, and the ferromagnetic resonance linewidth of the sample is measured under the combined action of the microwave field generated by the network analyzer and the magnetic field generated by an electromagnet. However, the network analyzer has the following technical problems: 1. The maximum output power is small (generally only up to 10 dBm in the low-frequency band and generally only up to 0 dBm in the high-frequency band); 2. The dynamic range of the receiving end is small and it is difficult to measure small signals; 3. The price of the network analyzer is expensive, etc. Summary of the Invention

[0003] The present invention provides an automatic test system and method for ferromagnetic resonance linewidth in view of the problems of the prior art. The spectrum analyzer readings affected by the sample at different frequencies and different magnetic field intensities are read by point-by-point scanning, and then the ferromagnetic resonance linewidth result of the sample is obtained by curve fitting of three groups of data: frequency, magnetic field intensity, and power. The present invention uses a combination scheme of a signal generator and a spectrum analyzer, and the price of a signal generator and a spectrum analyzer with the same highest frequency configuration is lower than that of a network analyzer.

[0004] To solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides an automatic test system for ferromagnetic resonance linewidth, which includes a main control unit, a signal generator, a spectrum analyzer, a magnetic field generating device, a gaussmeter, a microwave transmission structure, and two attenuators. The signal generator, the spectrum analyzer, the magnetic field generating device, and the gaussmeter are respectively electrically connected to the main control unit. One of the attenuators is connected between the signal generator and the microwave transmission structure, and the other attenuator is connected between the microwave transmission structure and the spectrum analyzer. A crystal oscillator synchronization line is connected between the spectrum analyzer and the signal generator. The gaussmeter is used to measure the magnetic field intensity of the magnetic field generating device, and the microwave transmission structure is used to load the sample.

[0006] Wherein, the microwave transmission structure is a planar waveguide.

[0007] Wherein, the microwave transmission structure is a coupling cavity.

[0008] Among them, the magnetic field generating device includes an electromagnet controller and two electromagnet bodies arranged opposite to each other, the microwave transmission structure is located at the center between the two electromagnet bodies, and the electromagnet controller is electrically connected to the main control unit.

[0009] Among them, the gaussmeter is provided with a gaussmeter probe extension wire, and the gaussmeter probe extension wire extends into the center between the two electromagnet bodies.

[0010] Among them, the signal generator, spectrum analyzer, electromagnet controller, and gaussmeter are respectively communicatively connected to the main control unit through a USB communication cable, a GPIB interface card, a network cable, and an RS232 interface line.

[0011] The present invention also provides an automatic test method for ferromagnetic resonance linewidth, which includes the following steps:

[0012] Step S1: The signal generator, spectrum analyzer, magnetic field generating device, and gaussmeter are powered on and warmed up for 30 minutes respectively. After warming up, the spectrum analyzer performs self-calibration operation.

[0013] Step S2: The signal generator, spectrum analyzer, magnetic field generating device, and gaussmeter are respectively electrically connected to the main control unit for device control and data transmission; a crystal oscillator synchronization wire is used to connect the crystal oscillator synchronization ports of the signal generator and the spectrum analyzer to synchronize the crystal oscillators of the signal generator and the spectrum analyzer.

[0014] Step S3: The microwave transmission structure is placed at the center position between the two electromagnet bodies of the magnetic field generating device.

[0015] Step S4: The main control unit controls the spectrum analyzer to set its reference level, sweep width, and resolution bandwidth for initialization settings. The main control unit controls the signal generator to output a specified RF power, keeps the output power of the signal generator unchanged, controls the center frequencies of the signal generator and the spectrum analyzer to be the same, and synchronously increases their center frequency setting values point by point according to preset parameters. After each change of the frequency value, the main control unit controls the spectrum analyzer to read the current frequency and maximum power and save them in the database of the main control unit.

[0016] Step S5: After loading the sample in the microwave transmission structure, the main control unit controls the signal generator to output a specified RF power, and the main control unit controls the magnetic field generating device to generate a magnetic field with a specified magnetic field intensity and returns the magnetic field reading to the main control unit through the gaussmeter.

[0017] Step S6: Increase the magnetic field intensity generated by the electromagnet point by point according to the preset value. After each magnetic field intensity is stabilized, the returned magnetic field reading is saved in the database of the main control unit, and the operation of Step S4 is repeated until the data under all magnetic field intensities are measured.

[0018] Advantages of the present invention:

[0019] The present invention reads the readings of a spectrum analyzer affected by a sample at different frequencies and different magnetic field strengths through point-by-point scanning, and then obtains the ferromagnetic resonance linewidth result of the sample by fitting data curves based on three groups of data of frequency, magnetic field strength, and power. The present invention uses a combined scheme of a signal generator and a spectrum analyzer, and its advantages are as follows: The signal generator can output a larger microwave power, generally above 20 dBm, and if necessary, a power amplifier can be externally connected to the signal generator to further amplify the signal, which has a positive effect on samples with weak signal responses; The spectrum analyzer is internally equipped with a preamplifier and can measure microwave signal changes as low as -140 dBm, which is more conducive to the collection of tiny signals; The price of a signal generator and a spectrum analyzer with the same highest frequency configuration is lower than that of a network analyzer. Description of the Drawings

[0020] Figure 1 It is a schematic block diagram of an automatic test system for ferromagnetic resonance linewidth of the present invention.

[0021] Figure 2 It is a flowchart of an automatic test method for ferromagnetic resonance linewidth of the present invention. Detailed Embodiments

[0022] For the convenience of understanding by those skilled in the art, the present invention will be further described below in conjunction with embodiments and the drawings. The content mentioned in the embodiments does not limit the present invention. The present invention will be described in detail below in conjunction with the drawings.

[0023] Embodiment 1

[0024] In Embodiment 1 of the present application, as Figure 1As shown in the figure, an automatic test system for ferromagnetic resonance linewidth includes a main control unit, a signal generator, a spectrum analyzer, a magnetic field generating device, a gaussmeter, a microwave transmission structure, and two attenuators. The signal generator, the spectrum analyzer, the magnetic field generating device, and the gaussmeter are respectively electrically connected to the main control unit. One of the attenuators is connected between the signal generator and the microwave transmission structure, and the other attenuator is connected between the microwave transmission structure and the spectrum analyzer. A crystal oscillator synchronization line is connected between the spectrum analyzer and the signal generator. The gaussmeter is used to measure the magnetic field strength of the magnetic field generating device, and the microwave transmission structure is used to load samples. The main control unit is a main control computer. Among them, the magnetic field generating device includes an electromagnet controller and two electromagnet bodies arranged opposite to each other. The microwave transmission structure is located at the center between the two electromagnet bodies. The electromagnet controller is electrically connected to the main control unit. Among them, the gaussmeter is provided with a gaussmeter probe extension line, and the gaussmeter probe extension line extends into the center between the two electromagnet bodies.

[0025] Specifically, the embodiment of the present application is ingeniously designed. The main control computer controls and transmits data by connecting the electromagnet controller, the signal generator, the spectrum analyzer, and the gaussmeter. A crystal oscillator synchronization line is used to connect the crystal oscillator synchronization ports of the signal generator and the spectrum analyzer to synchronize the crystal oscillators of the two instruments. The microwave transmission structure is placed at the center between the two electromagnets. At this time, no sample is placed in the microwave transmission structure. The main control computer controls the spectrum analyzer to automatically set its initial settings such as the reference level, sweep width, and resolution bandwidth. The main control computer controls the signal generator to output a specified radio frequency power and keeps the output power of the signal generator unchanged. The main control computer controls the center frequencies of the signal generator and the spectrum analyzer to be the same and increases their center frequency setting values synchronously point by point according to the preset parameters. After each change in the frequency value, the main control computer controls the spectrum analyzer to read the current frequency and maximum power and store them in the database of the main control computer. After loading the sample in the microwave transmission structure, the main control computer controls the two electromagnet bodies to generate a magnetic field with a specified magnetic field strength and returns the magnetic field reading to the main control computer through the gaussmeter. After the magnetic field is stable, the magnetic field strength generated by the electromagnet is increased point by point according to the preset value, and the above operations are repeated after each magnetic field strength is stable until all the data at all magnetic field strengths are measured. The system will scan point by point to read the readings of the spectrum analyzer affected by the sample at different frequencies and different magnetic field strengths, and then obtain the ferromagnetic resonance linewidth result of the sample through data curve fitting based on the three groups of data of frequency, magnetic field strength, and power.

[0026] The embodiment of the present application uses a combined solution of a signal generator and a spectrum analyzer. Its advantages are as follows: The signal generator can output a larger microwave power, generally above 20 dBm. If necessary, a power amplifier can be externally connected to the signal generator to further amplify the signal, which has a positive effect on samples with weak signal responses. The spectrum analyzer is built-in with a preamplifier and can measure microwave signal changes as low as -140 dBm, which is more conducive to the collection of weak signals. The price of a signal generator and a spectrum analyzer with the same highest frequency configuration is lower than that of a network analyzer.

[0027] In the embodiment of the present application, the microwave transmission structure is a planar waveguide or a coupling cavity. Specifically, the loading form of the sample is determined according to the nature of the sample. If the sample is powder, a coupling cavity is used; if the sample is a thin film, a planar waveguide is used.

[0028] In the embodiment of the present application, the signal generator, the spectrum analyzer, the electromagnet controller, and the gaussmeter are respectively communicatively connected to the main control unit through a USB communication cable, a GPIB interface card, a network cable, and an RS232 interface line. Specifically, the RF cable is respectively connected between the RF output port of the signal generator - attenuator - planar waveguide (or coupling cavity) - attenuator - RF input port of the spectrum analyzer. The spectrum analyzer and the signal generator are connected using a BNC signal line, and the spectrum analyzer outputs a crystal oscillator synchronization signal to the signal generator.

[0029] Embodiment 2

[0030] In the second embodiment of the present application, as Figure 2 shown, a method for automatically measuring the ferromagnetic resonance linewidth is provided, which includes the following steps:

[0031] Step S1: The signal generator, the spectrum analyzer, the magnetic field generating device, and the gaussmeter are powered on and respectively warmed up for 30 minutes. After warming up, the spectrum analyzer performs a self-calibration operation.

[0032] Step S2: The signal generator, the spectrum analyzer, the magnetic field generating device, and the gaussmeter are respectively electrically connected to the main control unit for device control and data transmission; a crystal oscillator synchronization line is used to connect the crystal oscillator synchronization ports of the signal generator and the spectrum analyzer to synchronize the crystal oscillators of the signal generator and the spectrum analyzer.

[0033] Step S3: The microwave transmission structure is placed at the central position between the two electromagnet bodies of the magnetic field generating device.

[0034] Step S4: The main control unit controls the spectrum analyzer to perform initialization settings for its reference level, sweep width, and resolution bandwidth. The main control unit controls the signal generator to output a specified RF power, keeps the output power of the signal generator unchanged, controls the center frequency of the signal generator and the spectrum analyzer to be the same, and synchronously increases the set value of its center frequency point by point according to the preset parameters. After each change in the frequency value, the main control unit controls the spectrum analyzer to read the current frequency and maximum power and stores them in the database of the main control unit;

[0035] Step S5: After loading the sample in the microwave transmission structure, the main control unit controls the signal generator to output a specified RF power, and controls the magnetic field generating device to generate a magnetic field with a specified magnetic field intensity and return the magnetic field reading to the main control unit through a gaussmeter;

[0036] Step S6: Increase the magnetic field intensity generated by the electromagnet point by point according to the preset value. After each magnetic field intensity stabilizes, store the returned magnetic field reading in the database of the main control unit, and repeat the operation of Step S4 until all data under all magnetic field intensities are measured.

[0037] Specifically, in the embodiment of the present application, through the above step method, the readings of the spectrum analyzer affected by the sample at different frequencies and different magnetic field intensities are scanned and read point by point, and then the ferromagnetic resonance linewidth result of the sample is obtained by fitting the data curves based on the three groups of data of frequency, magnetic field intensity, and power.

[0038] As mentioned above, it is only a preferred embodiment of the present invention, and there is no limitation to the present invention in any form. Although the present invention is disclosed above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, when making some changes or modifications using the above-disclosed technical content as equivalent change equivalent embodiments, but as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments according to the technical meaning of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. An automatic test system for ferromagnetic resonance linewidth, characterized in that: It includes a main control unit, a signal generator, a spectrum analyzer, a magnetic field generating device, a gaussmeter, a microwave transmission structure and two attenuators. The signal generator, the spectrum analyzer, the magnetic field generating device and the gaussmeter are respectively electrically connected to the main control unit. One of the attenuators is connected between the signal generator and the microwave transmission structure, and the other attenuator is connected between the microwave transmission structure and the spectrum analyzer. A crystal oscillator synchronization line is connected between the spectrum analyzer and the signal generator. The gaussmeter is used to measure the magnetic field intensity of the magnetic field generating device, and the microwave transmission structure is used to load samples.

2. The automatic measurement system for ferromagnetic resonance linewidth according to claim 1, wherein: The microwave transmission structure is a planar waveguide.

3. The automatic test system for ferromagnetic resonance linewidth according to claim 1, wherein: The microwave transmission structure is a coupled cavity.

4. An automatic test system for ferromagnetic resonance linewidth according to claim 1, characterized in that: The magnetic field generating device includes an electromagnet controller and two electromagnet bodies arranged opposite to each other. The microwave transmission structure is located at the center between the two electromagnet bodies, and the electromagnet controller is electrically connected to the main control unit.

5. The automatic test system for ferromagnetic resonance linewidth according to claim 4, characterized in that: The gaussmeter is provided with a gaussmeter probe extension wire, and the gaussmeter probe extension wire extends into the center between the two electromagnet bodies.

6. The automatic test system for ferromagnetic resonance linewidth according to claim 4, wherein: The signal generator, the spectrum analyzer, the electromagnet controller and the gaussmeter are respectively communicatively connected to the main control unit through a USB communication cable, a GPIB interface card, a network cable and an RS232 interface line.

7. An automatic test method for ferromagnetic resonance linewidth, characterized in that, It includes the following steps: Step S1: The signal generator, the spectrum analyzer, the magnetic field generating device and the gaussmeter are powered on and warmed up for 30 minutes respectively. After warming up, the spectrum analyzer performs a self-calibration operation. Step S2: The signal generator, the spectrum analyzer, the magnetic field generating device and the gaussmeter are respectively electrically connected to the main control unit for device control and data transmission. The crystal oscillator synchronization line is used to connect the crystal oscillator synchronization ports of the signal generator and the spectrum analyzer to synchronize the crystal oscillators of the signal generator and the spectrum analyzer. Step S3: The microwave transmission structure is placed at the center position between the two electromagnet bodies of the magnetic field generating device. Step S4: The main control unit controls the spectrum analyzer to set its reference level, sweep width and resolution bandwidth for initialization settings. The main control unit controls the signal generator to output a specified RF power, keeps the output power of the signal generator unchanged, controls the center frequencies of the signal generator and the spectrum analyzer to be the same, and synchronously increases their center frequency setting values point by point according to preset parameters. After each change of the frequency value, the main control unit controls the spectrum analyzer to read the current frequency and maximum power and save them in the database of the main control unit. Step S5: After loading the sample in the microwave transmission structure, the main control unit controls the signal generator to output a specified RF power, and controls the magnetic field generating device to generate a magnetic field with a specified magnetic field intensity and return the magnetic field reading to the main control unit through the gaussmeter. Step S6: Increase the magnetic field intensity generated by the electromagnet point by point according to the preset value. After each magnetic field intensity is stable, save the returned magnetic field reading in the database of the main control unit, and repeat the operation of Step S4 until all data under all magnetic field intensities are measured.

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