Electrical test platform, method for measuring resistance value of sample in magnetic field environment and method for observing magnetic domain motion

Abstract

The invention provides an electrical test platform, a method for measuring the resistance value of a sample in a magnetic field environment and a method for observing magnetic domain motion. The electrical test platform comprises a current source meter, a voltmeter, an electromagnet, a test base, an atomic force microscope, a first sample support and a second sample support. The first sample holder is used for bearing a sample, the current source meter and the voltmeter can be electrically connected with the test base, the current source meter is used for providing current for the sample, and the voltmeter is used for measuring the voltage of the sample and measuring the resistance of the sample in a magnetic field environment. The second sample holder is used for placing a sample, the second sample holder can be fixedly arranged in the atomic force microscope, and the current source meter can be electrically connected with the sample and is used for observing magnetic domain motion of the sample in a current environment.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical testing, and in particular to an electrical testing platform, a method for measuring the resistance of a sample in a magnetic field environment, and a method for observing the movement of magnetic domains. Background Art

[0002] When a magnetic field is applied to a metal or semiconductor with current flowing through it, its resistance value will change significantly. This phenomenon is called the magnetoresistance effect. In addition, in the process of spontaneous magnetization, ferromagnetic materials produce small magnetized regions with different directions, namely magnetic domains, to reduce static magnetic energy. When studying the magnetoresistance effect or conducting other experiments, the existing electrical test platform is often limited by the accuracy and stability of the test equipment for measuring low resistance and micro resistance. Especially in a magnetic field environment, traditional test methods are susceptible to electromagnetic interference, resulting in inaccurate measurement results. For the observation of magnetic domains, the existing technology mostly uses the magneto-optical Kerr measurement system (moke), which is an optical-based magnetic test system and is restricted by the transparency of the material. However, it is difficult to observe the surface morphology of the sample and the changes in the magnetic domain under the condition that the sample is passed through a current by the magnetic force microscope (MFM) technology. Therefore, there is an urgent need for an electrical test platform that can measure the resistance of the sample in a magnetic field environment and observe the movement of the magnetic domain. Summary of the invention

[0003] In view of this, embodiments of the present invention provide an electrical testing platform, a method for measuring the resistance of a sample in a magnetic field environment, and a method for observing the movement of magnetic domains, so as to eliminate or improve one or more defects existing in the prior art.

[0004] A first aspect of the present invention provides an electrical test platform, comprising: a current source meter, a voltmeter, an electromagnet, a test base, an atomic force microscope, a first sample holder, and a second sample holder; Wherein, the first sample holder comprises a housing, a first circuit board and a rotation driving mechanism; The first circuit board is arranged inside the housing for carrying the sample, the first circuit board is electrically connected to the sample, and the rotation drive mechanism is arranged inside the housing and connected to the first circuit board, for driving the first circuit board to rotate around a first axis; The test base is arranged below the housing for fixing the housing, and the test base can be electrically connected to the first circuit board; The electromagnets are arranged on both sides of the housing to provide a magnetic field; The current source meter and the voltage meter can both be electrically connected to the test base, the current source meter is used to provide current to the sample, and the voltage meter is used to measure the voltage of the sample, and is used to measure the resistance of the sample in a magnetic field environment; The second sample holder is used for placing the sample, and the second sample holder can be fixedly arranged in the atomic force microscope. The current source meter can be electrically connected to the sample to observe the magnetic domain movement of the sample in a current environment.

[0005] In some embodiments of the present invention, the rotation drive mechanism includes a first bevel gear, a connecting shaft, a first gear, a second gear, a third gear and a rotating disk; Wherein, the two ends of the connecting shaft are rotatably connected to the inner walls opposite to the outer shell respectively; The first bevel gear and the first gear are both fixedly connected to the connecting shaft and are coaxially arranged, and the first bevel gear and the first gear are respectively arranged close to the inner walls opposite to each other of the housing; The second gear and the third gear are both rotatably connected to the inner wall of the housing, and the second gear is meshingly connected with the first gear and the third gear; The rotating disk is rotatably disposed on the inner wall of the housing and corresponds to the position of the third gear. Two sides of the first circuit board are fixedly connected to the third gear and the rotating disk respectively.

[0006] In some embodiments of the present invention, the rotation drive mechanism further includes a fourth gear, a fifth gear and a torsion spring; Wherein, the fourth gear and the fifth gear are rotatably connected to the inner wall of the housing, and the fourth gear is meshingly connected with the third gear and the fifth gear; Two ends of the torsion spring are respectively connected to the fifth gear and the inner wall of the housing.

[0007] In some embodiments of the present invention, the first sample holder further comprises a motor and a second bevel gear; The second bevel gear is fixedly arranged on the output shaft of the motor, and the second bevel gear is matched with the first bevel gear to drive the first bevel gear to rotate.

[0008] In some embodiments of the present invention, the housing is a columnar structure, and the housing includes an integrally formed fixing ring, two connecting plates and a bottom bracket; The two connecting plates are symmetrically arranged, the two ends of the connecting plates are respectively connected to the fixing ring and the bottom bracket, and the rotation driving mechanism is arranged between the two connecting plates.

[0009] In some embodiments of the present invention, the first circuit board has a plurality of first contacts, and the first contacts are electrically connected to the sample; A plurality of pins are arranged on one side of the base away from the fixing ring, the plurality of pins are arranged in a circle, and one end of the pins is connected to the first contact point through a wire; The test base includes a base body, and a plurality of pinholes and a plurality of wiring holes arranged on the base body; Wherein, the plurality of pinholes are arranged in a circular shape, and the pinholes are adapted to the insertion pins; The wiring hole is electrically connected to the pinhole, and the wiring hole is used to electrically connect to the current source meter and the voltage meter.

[0010] In some embodiments of the present invention, the second sample holder includes a second circuit board, a plurality of second contacts, and at least two plugs; Among them, the multiple second contacts are arranged on the second circuit board, the second contacts are connected to the sample through wires, one end of the plug is electrically connected to the second contacts, and the other end of the plug is used to connect to the current source meter.

[0011] In some embodiments of the present invention, the electrical test platform further comprises a host and an electromagnet controller; wherein the electromagnet controller is electrically connected to the electromagnet for controlling the magnitude of the magnetic field, and the host is electrically connected to the current source meter, the voltmeter, the electromagnet controller and the atomic force microscope; The output current of the current source meter is 4pA to 20mA, and the range of the voltage meter is μV to 200V.

[0012] A second aspect of the present invention provides a method for measuring the resistance of a sample in a magnetic field environment. Based on the electrical test platform, the method comprises the following steps: Fixing the sample on the first circuit board, fixing the housing on the test base, and connecting the current source meter and the voltage meter to the test base; Control the electromagnet to apply a magnetic field to the sample, control the current source meter to pass current to the sample, obtain the voltage of the sample measured by the voltmeter, and calculate the resistance value of the sample; The driving mechanism is controlled to drive the sample to rotate so that the sample forms a specific angle with the magnetic field, and the resistance value when the sample and the magnetic field form a specific angle is measured.

[0013] The third aspect of the present invention provides a method for observing magnetic domain movement. Based on the electrical test platform, the method comprises the following steps: Fixing the sample on the second sample holder, fixing the second sample holder on the test position of the atomic force microscope, and connecting the current source meter to the second sample holder; The probe of the atomic force microscope is controlled to be placed above the sample, the current source is controlled to supply current to the sample, the current source is controlled to be powered off and the atomic force microscope is started to scan at the same time, and the scanning time is shorter than the relaxation time for the sample to recover its original shape.

[0014] The electrical testing platform, the method for measuring the resistance of a sample in a magnetic field environment, and the method for observing the movement of magnetic domains of the present invention have the following technical effects: the electrical testing platform cooperates with the method for measuring the resistance of a sample in a magnetic field environment to accurately measure the resistance of the sample in a magnetic field environment, and the electrical testing platform cooperates with the method for observing the movement of magnetic domains to observe the movement of magnetic domains in a current environment, wherein the first sample holder is used to measure the resistance, and can carry the sample and drive the sample to rotate, so that the sample and the magnetic field are at different angles, and the electromagnet can provide the sample with a stable magnetic field of a certain strength, so as to facilitate the measurement of the resistance of the sample at different angles to the magnetic field; the second sample holder is used to observe the magnetic domain of the sample, and can be suitable for samples with a certain thickness and opaque, and the atomic force microscope can not only observe the movement of the magnetic domain but also observe the surface morphology of the sample.

[0015] Additional advantages, purposes, and features of the present invention will be described in part in the following description, and will become apparent to those skilled in the art after studying the following, or may be learned from the practice of the present invention. The purposes and other advantages of the present invention may be achieved and obtained by the structures specifically indicated in the specification and the accompanying drawings.

[0016] Those skilled in the art will appreciate that the objectives and advantages that can be achieved with the present invention are not limited to the above specific description, and the above and other objectives that can be achieved by the present invention will be more clearly understood from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of this application, and do not constitute a limitation of the present invention. The components in the drawings are not drawn to scale, but are only for illustrating the principles of the present invention. In order to facilitate the illustration and description of some parts of the present invention, the corresponding parts in the drawings may be enlarged, that is, they may become larger relative to other components in the exemplary device actually manufactured according to the present invention. In the drawings: Figure 1 Schematic diagram of the structure of an electrical testing platform in one embodiment of the present invention.

[0018] Figure 2 FIG. 4 is a schematic structural diagram of a first sample holder in an embodiment of the present invention.

[0019] Figure 3 FIG. 4 is a bottom view of a first sample holder according to an embodiment of the present invention.

[0020] Figure 4 Schematic diagram of the structure of a test base in one embodiment of the present invention.

[0021] Figure 5 FIG. 4 is a schematic diagram of the structure of the second sample holder in one embodiment of the present invention.

[0022] Figure 6The figure is a flow chart of a method for measuring the resistance of a sample in a magnetic field environment according to an embodiment of the present invention.

[0023] Figure 7 Flow chart of a method for observing magnetic domain movement in one embodiment of the present invention.

[0024] Figure numerals: 1. current source meter; 2. voltmeter; 3. host; 4. electromagnet; 5. first sample holder; 6. test base; 7. electromagnet controller; 8. atomic force microscope; 9. second sample holder; 501. housing; 502. first bevel gear; 503. connecting shaft; 504. first gear; 505. second gear; 506. third gear; 507. first circuit board; 508. first contact; 509. turntable; 510. sample; 511. fourth gear; 512. fifth gear; 513. torsion spring; 514. pin; 515. motor; 516. second bevel gear; 601. base body; 602. pinhole; 603. wiring hole; 901. second circuit board; 902. second contact; 903. plug. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0026] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions according to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0027] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, elements, steps or components, but does not exclude the presence or addition of one or more other features, elements, steps or components.

[0028] It should also be noted that, unless otherwise specified, the term “connection” herein may refer not only to a direct connection but also to an indirect connection involving an intermediate.

[0029] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same or similar components, or the same or similar steps.

[0030] In order to solve the technical problems of low measurement accuracy of low resistance and micro resistance and difficulty in observing magnetic domain movement of opaque materials in electrical testing platforms in the prior art, the embodiments of the present invention provide an electrical testing platform, a method for measuring sample resistance in a magnetic field environment, and a method for observing magnetic domain movement, which improves the resistance measurement accuracy and can observe magnetic domain movement for opaque materials.

[0031] The electrical transport property is one of the most basic and important physical properties of matter (or material), reflecting the basic physical behaviors related to charge, such as the law of change of resistance and Hall resistance with temperature, magnetic field, and pressure, as well as related physical effects such as Shubnikov-de Haas quantum oscillation, quantum Hall effect, etc., and is one of the most important properties in comprehensive physical properties. In the prior art, a multimeter is usually used to measure resistance, which has poor accuracy and the electromagnetic induction generated by the internal circuit under the magnetic field will affect the accuracy. The electrical test platform of the embodiment of the present invention can perform electrical transport testing on the resistance of a device or sample in a magnetic field environment.

[0032] Molecules or atoms are the basic elements that make up material. The movement of electrons around the nucleus in the basic element forms an electric current. The magnetic field generated by the current makes each basic element equivalent to a tiny magnet. A large number of basic elements form a group structure. The magnetic fields generated by all basic elements in the group are neatly arranged in the same direction. Such a group is called a magnetic domain. The electrical test platform of the embodiment of the present invention can observe the movement of the sample magnetic domain in the current environment.

[0033] Reference Figure 1 The first aspect of the embodiment of the present invention provides an electrical test platform, including: a current source meter 1, a voltmeter 2, an electromagnet 4, a test base 6, an atomic force microscope 8, a first sample holder 5 and a second sample holder 9. The above instruments and components can be placed on the test table.

[0034] Reference Figure 2 The first sample holder 5 includes a housing 501, a first circuit board 507 and a rotation drive mechanism. The first circuit board 507 is arranged inside the housing 501 for carrying a sample 510, and the first circuit board 507 is electrically connected to the sample 510. The rotation drive mechanism is arranged inside the housing 501 and connected to the first circuit board 507, and is used to drive the first circuit board 507 to rotate around a first axis; the sample 510 can be fixed on the first circuit board 507 by gluing or welding.

[0035] The test base 6 is arranged under the outer shell 501 for fixing the outer shell 501, and the test base 6 can be electrically connected to the first circuit board 507; the test base 6 and the first sample holder 5 are arranged separately, and the first sample holder 5 can be plugged into the test base 6 through the outer shell 501 and form an electrical connection, so that the electrical signal in the first sample holder 5 can be transmitted to the test base 6.

[0036] It should be noted that the electromagnets 4 are disposed on both sides of the housing 501 to provide a magnetic field. Figure 2 When the first circuit board 507 and the plane where the sample is located are in a vertical state, the direction of the magnetic field is parallel to the sample.

[0037] The current source meter 1 and the voltmeter 2 can both be electrically connected to the test base 6. The current source meter 1 is used to provide current to the sample 510, and the voltmeter 2 is used to measure the voltage of the sample 510, and is used to measure the resistance of the sample 510 in a magnetic field environment. The current source meter 1 can use a high-precision current source meter, such as a Keithley 6221 current source meter, and the voltmeter 2 can use an ultra-low noise voltmeter, such as a Keithley 2182A voltmeter. The current parameters and voltage parameters of the sample can be accurately measured by the high-precision current source meter 1 and voltmeter 2, and the resistance value of the sample can be obtained by taking the voltage parameter and the current parameter as the quotient.

[0038] Reference Figure 5 The second sample holder 9 is used to place the sample 510. The second sample holder 9 can be fixedly arranged in the atomic force microscope 8. The current source meter 1 can be electrically connected to the sample 510 to observe the magnetic domain movement of the sample 510 under the current environment. The sample 510 is usually in a cross shape or a strip shape. The end of the sample 510 is an electrode with a larger area, so as to facilitate the fixation of the sample and the second sample holder 9 and the connection with the wire.

[0039] Specifically in the above embodiment, the electrical test platform can accurately measure the resistance of the sample in a magnetic field environment, and can observe the movement of magnetic domains in a current environment, wherein the first sample holder 5 is used to measure the resistance, which can carry the sample and drive the sample to rotate, so that the sample and the magnetic field are at different angles, and the electromagnet 4 can provide a stable magnetic field of a certain strength to the sample, which is convenient for measuring the resistance of the sample at different angles to the magnetic field; the second sample holder 9 is used to observe the magnetic domains of the sample, and can be suitable for samples with a certain thickness and opaqueness, and the atomic force microscope 8 can not only observe the movement of magnetic domains but also observe the surface morphology of the sample.

[0040] In heterojunction structures composed of magnetic materials or heavy metals, the electronic configuration of the material will change in a magnetic field environment, resulting in a magnetoresistance effect in the sample. One of the research directions of spin electronics is to explore various magnetoresistance effects, which require measuring electrical signals in a magnetic field environment. In the prior art, there is no test platform that can specifically test the resistance of a sample at different angles to the magnetic field.

[0041] In this embodiment, the substrate of the test sample is a 5*5*1mm thin sheet, which is coated and micro-nano-processed into a small device for testing. The direction of the input current is the x-axis, the out-of-plane direction, i.e., the direction perpendicular to the sample surface, is the z-axis, and the other direction is the y-axis. The angle between the magnetic field and the x-axis, the y-axis, or the z-axis is changed. In this case, various magnetoresistances of the sample are tested, including spin Hall magnetoresistance, etc. Changing the angle between the magnetic field and the three axes is generally carried out by rotating the sample, i.e., angle resistance test.

[0042] In some embodiments, the rotation drive mechanism includes a first bevel gear 502, a connecting shaft 503, a first gear 504, a second gear 505, a third gear 506 and a rotating disk 509. The two ends of the connecting shaft 503 are respectively rotatably connected to the inner wall opposite to the housing 501. The first bevel gear 502 and the first gear 504 are both fixedly connected to the connecting shaft 503 and coaxially arranged, and the first bevel gear 502 and the first gear 504 are respectively arranged near the inner wall opposite to the housing 501. The second gear 505 and the third gear 506 are both rotatably connected to the inner wall of the housing 501, and the second gear 505 is meshedly connected with the first gear 504 and the third gear 506. The rotating disk 509 is rotatably arranged on the inner wall of the housing 501 and corresponds to the position of the third gear 506. The two sides of the first circuit board 507 are respectively fixedly connected to the third gear 506 and the rotating disk 509.

[0043] In the above embodiment, the first bevel gear 502 can be driven manually or with a special tool. The first bevel gear 502 drives the first gear 504 to rotate through the connecting shaft 503. The first gear 504 transmits power to the second gear 505, and the second gear 505 drives the third gear 506 to rotate. Since the first circuit board 507 is fixed on the third gear 506 and the turntable 509, the first circuit board 507 rotates synchronously with the third gear 506 and the turntable 509, so that the angle of the first circuit board 507 can be adjusted, so that the first circuit board 507 can have different angles with the magnetic field.

[0044] In some embodiments, the rotation drive mechanism further includes a fourth gear 511, a fifth gear 512 and a torsion spring 513. The fourth gear 511 and the fifth gear 512 are rotationally connected to the inner wall of the housing 501, and the fourth gear 511 is meshedly connected with the third gear 506 and the fifth gear 512. The two ends of the torsion spring 513 are respectively connected to the fifth gear 512 and the inner wall of the housing 501. Figure 2The torsion spring 513 has no elastic force in the initial position. When the first circuit board 507 rotates a certain angle, the fourth gear 511 and the fifth gear 512 will rotate synchronously, so that the torsion spring 513 rotates a certain angle. The torsion spring 513 stores a certain elastic force. When the test is completed, the elastic force stored in the torsion spring 513 is released, so that the first circuit board 507 returns to the vertical plane, that is, the initial position of the first circuit board 507 is convenient for the next measurement.

[0045] In some embodiments, the first sample holder 5 further includes a motor 515 and a second bevel gear 516. The second bevel gear 516 is fixedly disposed on the output shaft of the motor 515, and the second bevel gear 516 is adapted to the first bevel gear 502 to drive the first bevel gear 502 to rotate. Figure 2 The motor 515 can drive the second bevel gear 516 to rotate. The output shaft of the motor 515 has a certain length, so that the second bevel gear 516 can extend into the interior of the housing 501 to engage with the first bevel gear 502. When the motor 515 rotates, it can drive the first bevel gear 502 to rotate, thereby controlling the change in the angle between the first circuit board 507 and the sample.

[0046] In some embodiments, the housing 501 is a cylindrical structure, and the housing 501 includes an integrally formed fixing ring, two connecting plates and a bottom bracket. The two connecting plates are symmetrically arranged, and the two ends of the connecting plates are respectively connected to the fixing ring and the bottom bracket, and the rotation drive mechanism is arranged between the two connecting plates. The housing 501 can be made of metal, such as copper. When the sample is tested, the axis of the housing 501 is in a vertical state, and the housing 501 has a large-area hollow structure to prevent the magnetic field from being affected. The prior art usually uses a multimeter to measure resistance, which has poor accuracy and the electromagnetic induction generated by the internal circuit under the magnetic field will affect the accuracy. In this embodiment, the accuracy of the electrical test platform is greatly improved compared to the multimeter.

[0047] In some embodiments, the first circuit board 507 has a plurality of first contacts 508, and 10-15 contacts may be selected. The first contacts 508 are electrically connected to the sample 510. The sample 510 may be electrically connected to the first contacts 508 via a wire. Figure 3 A plurality of pins 514 are provided on one side of the bottom bracket away from the fixing ring, and 10 to 15 pins may be selected. The plurality of pins 514 are arranged in a circle, and one end of the pin 514 is connected to the first contact 508 through a wire.

[0048] Reference Figure 4The test base 6 includes a base body 601, and a plurality of pinholes 602 and a plurality of wiring holes 603 arranged on the base body 601, and 10-15 of the pinholes 602 can be selected. Among them, the plurality of pinholes 602 are arranged in a circle, and the pinholes 602 are adapted to the plug pins 514; the wiring holes 603 are electrically connected to the pinholes 602, and the wiring holes 603 are used to be electrically connected to the current source meter 1 and the voltmeter 2. The current provided by the current source meter 1 passes through the wiring hole 603, the pinhole 602, the plug pin 514, the connecting wire between the plug pin 514 and the first circuit board 507, the first contact 508, and the connecting wire between the first contact 508 and the sample in sequence, and is finally applied to the sample. Similarly, the voltmeter 2 also measures the voltage of the sample through the above circuit.

[0049] In some embodiments, the second sample holder 9 includes a second circuit board 901, a plurality of second contacts 902 and at least two plugs 903. Among them, the plurality of second contacts 902 are arranged on the second circuit board 901, the second contacts 902 are connected to the sample 510 through a wire, one end of the plug 903 is electrically connected to the second contact 902, and the other end of the plug 903 is used to connect to the current source meter 1. In the above embodiment, the second circuit board 901 can be selected from other shapes such as rectangle, square, circle, etc. The second circuit board 901 has a circuit, one end of the circuit forms the second contact 902, the other end of the circuit is connected to the plug 903, the second contact 902 is connected to the sample 510 through a wire, and the plug 903 can be connected to the current source meter 1. The second sample holder 9 loaded with the sample is placed in the atomic force microscope 8, and the second sample holder 9 is connected to the current source meter 1, so that the magnetic domain of the sample can be observed.

[0050] It should be noted that the magneto-optical Kerr measurement system (moke) in the prior art is an optical-based magnetic signal detection system. This system can realize in-situ observation of samples, but as this system is an optical-based test, it has extremely strict requirements on the thickness of the sample. The system requires that the sample cannot be too thick, otherwise the detection light cannot penetrate the sample. When doing the moke test, the sample thickness must be precisely controlled to obtain accurate results, and the moke test can only obtain magnetic information in a certain area. The test platform in this embodiment is based on electrical testing, so there is no requirement for sample thickness. At the same time, it can also scan the surface morphology and magnetic structure of the sample, and can simultaneously obtain the morphology and magnetic structure information in a certain area of ​​the sample. The above-mentioned in-situ observation refers to testing under certain conditions. For example, in this embodiment, the sample is tested after current is passed through it.

[0051] In some embodiments, the electrical test platform also includes a host 3 and an electromagnet controller 7. Among them, the electromagnet controller 7 is electrically connected to the electromagnet 4 for controlling the magnitude of the magnetic field, and the host 3 is electrically connected to the current source meter 1, the voltmeter 2, the electromagnet controller 7 and the atomic force microscope 8. The output current of the current source meter 1 is 4pA to 210mA, and the range of the voltmeter 2 is 1μV to 200V. The electromagnet controller 7 can control the magnitude of the magnetic field intensity of the electromagnet 4. The resistance of the sample under different magnetic field magnitudes can be tested according to experimental requirements. The host 3 can control the actions of each instrument in the test platform to realize automated experiments. For example, the host 3 can communicate with the current source meter 1 and the voltmeter 2 through the GPIB, LAN or USB interface, and use the labview programming software to realize remote control and data acquisition of the system. The test program can be written in the host 3, and the operation of the electromagnet 4, the current source meter 1, the voltmeter 2, the electromagnet controller 7 and the atomic force microscope 8 can be controlled by the test program to realize remote control and experiments.

[0052] The electrical test platform of the embodiment of the present invention has the following advantages: 1. High-precision measurement: The high-precision current output of Keithley 6221 and the ultra-low noise voltage measurement capability of 2182A are used to achieve accurate measurement of resistance values.

[0053] 2. Magnetic field environment: Provide a stable magnetic field environment through electromagnets to reduce the impact of external electromagnetic interference on the measurement results.

[0054] 3. Programmable control: supports remote control and automated testing to improve test efficiency and accuracy.

[0055] 4. Multifunctional test: The electrical test platform consists of the core 6221 current source meter and 2182A voltmeter. Different tests can be performed by changing the sample holder. The first sample holder can be used to test the corner resistance, and the second sample holder can be used to perform in-situ magnetic force microscope testing.

[0056] Reference Figure 6 A second aspect of an embodiment of the present invention provides a method for measuring the resistance of a sample in a magnetic field environment, based on an electrical test platform, the method comprising the following steps: S11, fixing the sample on the first circuit board, fixing the housing on the test base, and connecting the current source meter and the voltage meter to the test base; S12, controlling the electromagnet to apply a magnetic field to the sample, controlling the current source meter to pass current to the sample, obtaining the voltage of the sample measured by the voltmeter, and calculating the resistance value of the sample; S13, controlling the driving mechanism to drive the sample to rotate so that the sample forms a specific angle with the magnetic field, and measuring the resistance value when the sample and the magnetic field form the specific angle.

[0057] The traditional test method is to apply a magnetic field to the sample, connect the probe of the multimeter to the sample to be tested, and directly measure the resistance value of the sample. The circuits and electrical components inside the multimeter will produce electromagnetic induction in the magnetic field environment, affecting the accuracy. In this embodiment, the method for measuring the resistance value of the sample in the magnetic field environment does not require the use of a multimeter. A current is passed into the sample through a high-precision current source meter, and the voltage of the sample is measured by a low-noise voltmeter. The resistance value of the sample can be measured by taking the voltage and current as the quotient. In addition, the driving mechanism can drive the sample to rotate so that the sample forms a specific angle with the magnetic field, and the resistance value of the sample under the state of forming a specific angle with the magnetic field is measured, which is convenient for studying the influence of the angle between the magnetic field and the sample on the resistance of the sample.

[0058] Specifically, before the test, the output current value and frequency of the current source meter 1 and the magnetic field strength of the electromagnet 4 are set on the host 3. The current is a sine wave current, and the size can be selected as 1mA. After starting the test, the current source meter 1 provides a stable current to the sample, and the voltmeter 2 measures the voltage across the device. According to Ohm's law (R=U / I), the resistance value of the device is calculated and displayed and recorded in real time through the host 3. During the test, the output parameters of the current source meter and the magnetic field strength of the electromagnet can be adjusted in real time to meet different test requirements. At the same time, the first sample holder can be rotated to realize the rotation of the sample to test the change in resistance when the sample surface and the magnetic field are at different angles.

[0059] Reference Figure 7 A third aspect of an embodiment of the present invention provides a method for observing magnetic domain movement, based on an electrical test platform, the method comprising the following steps: S21, fixing the sample on the second sample holder, fixing the second sample holder on the test position of the atomic force microscope, and connecting the current source meter to the second sample holder; S22. Control the probe of the atomic force microscope to be placed above the sample, control the current source to supply current to the sample, control the current source to be powered off and start the atomic force microscope to scan at the same time, and the scanning time is shorter than the relaxation time for the sample to recover to its original shape.

[0060] The current magnetic force microscope (MFM) equipment is mainly integrated with the atomic force microscope (AFM). In the absence of an external current, the AFM tapping mode is used to scan the surface morphology of the sample, and then the probe is lifted to a certain height and suspended according to the morphology scanned by tapping to scan the sample again to obtain the magnetic signal. Because the tapping mode inevitably requires contact with the sample surface, and the MFM test probe is a magnetic needle, if a magnetic field or electric field is applied, it will directly damage the scanning needle tip, so it is difficult to break through the current in-situ MFM technology.

[0061] In the method for observing the movement of magnetic domains in the above-mentioned embodiment, in the original AFM test of BRUKER, after the needle is lowered, a current is passed through the sample using a current source meter and a second sample holder. At this time, since the needle tip is only lowered into place and the test contacting the sample has not started, the passing of current has no effect on the needle tip. After the current is passed, the magnetic structure of the sample is changed, and then the power is turned off and the MFM test is quickly started. After the magnetic structure of the sample surface is changed, its structure will return to its original state after the power is turned off, but the probe has been lowered into place and the current is passed through the AFM. At this time, the immediate test is still within the relaxation time for the sample to return to its original state, so the measured magnetic domain signal is valid, and the magnetic domain can be effectively observed.

[0062] Specifically, the output current value and frequency of the current source meter are set on the host 3 before the test. The current output by the current source meter is a pulse current with a frequency of 1-2 Hz. The current size can be selected as 3mA. The current source meter provides a stable current to the sample, passes the current into the sample, and changes the shape or size of the magnetic domain in the sample. The atomic force microscope works at room temperature and pressure. The atomic force microscope has a sample stage. The sample stage can adsorb the second sample holder by negative pressure. The probe is located above the second sample holder. The probe can be MESP type. The probe part can move up and down to complete the needle insertion and withdrawal operation. The sample stage is connected to the motor and can move back and forth. When scanning, the needle is first lowered until the needle is close to the sample surface. When the test starts, the sample stage will shake slightly to make the needle scan the sample back and forth to obtain test data.

[0063] It should be clear that the present invention is not limited to the specific configuration and processing described above and shown in the figures. For the sake of simplicity, a detailed description of the known method is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the present invention.

[0064] In the present invention, features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with features of other embodiments or replace features of other embodiments.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An electrical testing platform, characterized in that: include: A current source meter (1), a voltmeter (2), an electromagnet (4), a test base (6), an atomic force microscope (8), a first sample holder (5), and a second sample holder (9); Wherein, the first sample holder (5) comprises a housing (501), a first circuit board (507) and a rotation drive mechanism; The first circuit board (507) is arranged inside the housing (501) for carrying the sample (510), the first circuit board (507) is electrically connected to the sample (510), and the rotation drive mechanism is arranged inside the housing (501) and connected to the first circuit board (507), and is used to drive the first circuit board (507) to rotate around a first axis; The test base (6) is arranged below the housing (501) and is used to fix the housing (501); the test base (6) can be electrically connected to the first circuit board (507); The electromagnets (4) are arranged on both sides of the housing (501) and are used to provide a magnetic field; The current source meter (1) and the voltmeter (2) can both be electrically connected to the test base (6); the current source meter (1) is used to provide current to the sample (510); the voltmeter (2) is used to measure the voltage of the sample (510), and is used to measure the resistance of the sample (510) in a magnetic field environment; The second sample holder (9) is used to place a sample (510), and the second sample holder (9) can be fixedly arranged in the atomic force microscope (8). The current source meter (1) can be electrically connected to the sample (510) to observe the movement of magnetic domains of the sample (510) in an electric current environment.

2. The electrical testing platform according to claim 1, characterized in that: The rotation drive mechanism comprises a first bevel gear (502), a connecting shaft (503), a first gear (504), a second gear (505), a third gear (506) and a rotating disk (509); Wherein, both ends of the connecting shaft (503) are rotatably connected to the inner walls opposite to the outer shell (501); The first bevel gear (502) and the first gear (504) are both fixedly connected to the connecting shaft (503) and are coaxially arranged, and the first bevel gear (502) and the first gear (504) are respectively arranged close to opposite inner walls of the housing (501); The second gear (505) and the third gear (506) are both rotatably connected to the inner wall of the housing (501), and the second gear (505) is meshingly connected to the first gear (504) and the third gear (506); The rotating disk (509) is rotatably arranged on the inner wall of the housing (501) and corresponds to the position of the third gear (506), and two sides of the first circuit board (507) are fixedly connected to the third gear (506) and the rotating disk (509) respectively.

3. The electrical testing platform according to claim 2, characterized in that: The rotation drive mechanism further comprises a fourth gear (511), a fifth gear (512) and a torsion spring (513); The fourth gear (511) and the fifth gear (512) are rotatably connected to the inner wall of the housing (501), and the fourth gear (511) is meshingly connected to the third gear (506) and the fifth gear (512); Two ends of the torsion spring (513) are respectively connected to the fifth gear (512) and the inner wall of the housing (501).

4. The electrical testing platform according to claim 2, characterized in that: The first sample holder (5) further comprises a motor (515) and a second bevel gear (516); The second bevel gear (516) is fixedly arranged on the output shaft of the motor (515), and the second bevel gear (516) is adapted to the first bevel gear (502) and is used to drive the first bevel gear (502) to rotate.

5. The electrical testing platform according to claim 1, characterized in that: The housing (501) is a columnar structure, and comprises an integrally formed fixing ring, two connecting plates and a bottom bracket; The two connecting plates are symmetrically arranged, the two ends of the connecting plates are respectively connected to the fixing ring and the bottom bracket, and the rotation driving mechanism is arranged between the two connecting plates.

6. The electrical testing platform according to claim 5, characterized in that: The first circuit board (507) has a plurality of first contacts (508), and the first contacts (508) are electrically connected to the sample (510); A plurality of plug pins (514) are provided on a side of the base away from the fixing ring, the plurality of plug pins (514) are arranged in a circle, and one end of the plug pin (514) is connected to the first contact point (508) via a wire; The test base (6) comprises a base body (601), and a plurality of pinholes (602) and a plurality of wiring holes (603) arranged on the base body (601); The plurality of pinholes (602) are arranged in a circular shape, and the pinholes (602) are adapted to fit the insertion pins (514); The wiring hole (603) is electrically connected to the pinhole (602), and the wiring hole (603) is used to be electrically connected to the current source meter (1) and the voltage meter (2).

7. The electrical testing platform according to claim 1, characterized in that: The second sample holder (9) comprises a second circuit board (901), a plurality of second contacts (902) and at least two plugs (903); The plurality of second contacts (902) are arranged on the second circuit board (901), the second contacts (902) are connected to the sample (510) via a wire, one end of the plug (903) is electrically connected to the second contacts (902), and the other end of the plug (903) is used to be connected to the current source meter (1).

8. The electrical testing platform according to claim 1, characterized in that: The electrical testing platform further comprises a host (3) and an electromagnet controller (7); wherein the electromagnet controller (7) is electrically connected to the electromagnet (4) for controlling the magnitude of the magnetic field, and the host (3) is electrically connected to the current source meter (1), the voltmeter (2), the electromagnet controller (7) and the atomic force microscope (8); The output current of the current source meter (1) is 4pA to 210mA, and the range of the voltage meter (2) is 1μV to 200V.

9. A method for measuring the resistance of a sample in a magnetic field environment, based on the electrical test platform according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: Fixing the sample on the first circuit board, fixing the housing on the test base, and connecting the current source meter and the voltage meter to the test base; Control the electromagnet to apply a magnetic field to the sample, control the current source meter to pass current to the sample, obtain the voltage of the sample measured by the voltmeter, and calculate the resistance value of the sample; The driving mechanism is controlled to drive the sample to rotate so that the sample forms a specific angle with the magnetic field, and the resistance value when the sample and the magnetic field form a specific angle is measured.

10. A method for observing magnetic domain movement, based on the electrical test platform according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: Fixing the sample on the second sample holder, fixing the second sample holder on the test position of the atomic force microscope, and connecting the current source meter to the second sample holder; The probe of the atomic force microscope is controlled to be placed above the sample, the current source is controlled to supply current to the sample, the current source is controlled to be powered off and the atomic force microscope is started to scan at the same time, and the scanning time is shorter than the relaxation time for the sample to recover its original shape.

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