Variable temperature magnetic field probe test platform and method of operation

Abstract

The application discloses a variable-temperature magnetic field probe test platform and an operation method, and relates to the technical field of material testing. The variable-temperature magnetic field probe test platform comprises a Dewar, the Dewar comprises a vacuum bottle body, the vacuum bottle body provides a vacuum test environment for a sample, a low-temperature system and a superconducting magnet system are arranged in the vacuum bottle body, the superconducting magnet system comprises a superconducting magnet coil, and the low-temperature system cooperates with the superconducting magnet coil to couple a magnetic field and a low-temperature environment under the vacuum test environment. In the application, according to the required test temperature of the sample, the heat switch of the temperature control device is switched to switch the cooling temperature of the first cold plate to the sample and the cooling temperature of the second cold plate to the sample. Based on the cooling temperature, the temperature of the sample is precisely adjusted by using a heating rod until the temperature of the sample reaches the test temperature, so that the control precision of the temperature of the sample is higher, the temperature span is larger, the material property test range of the sample to be tested is further improved, and the sample is prevented from being limited by a single test temperature.

Description

Technical Field

[0001] This invention relates to the field of materials testing technology, and in particular to a variable-temperature magnetic field probe testing platform and its operating method. Background Technology

[0002] Probe station testing equipment is a widely used non-destructive testing method applicable to physics and semiconductor fields. Specifically, it can be used to test the electrical, optoelectronic, and high-frequency properties of materials or devices, with extensive applications in semiconductors and superconductivity. Building upon this foundation, magnetic field probe station testing systems further provide a magnetic field environment, enabling the equipment to further investigate the performance and characteristics of the tested materials or devices under magnetic fields. Typical applications include magnetism, spintronics, semiconductor physics and devices, and quantum devices.

[0003] In practical applications, since the final products of semiconductor or superconducting materials are used in low-temperature environments, it is necessary to test the performance of samples at low temperatures. Therefore, a magnetic field probe station capable of placing samples in a low-temperature environment is required. Current technologies typically use electromagnets to provide the magnetic field environment and a refrigerator to cool the sample. However, simultaneously applying a magnetic field and maintaining a low-temperature environment is difficult to achieve. Furthermore, the magnetic field strength and uniformity generated by electromagnets are poor, and the temperature after cooling by the refrigerator head is usually fixed. This makes it difficult to control the temperature of the sample during testing, or results in a small temperature range. Consequently, the testing range of the material properties of the sample is highly limited. Summary of the Invention

[0004] This invention provides a variable-temperature magnetic field probe testing platform and operating method, which can solve the problem mentioned in the background art that the testing range of material properties of the sample to be tested is highly limited.

[0005] A variable-temperature magnetic field probe testing platform, comprising:

[0006] A Dewar, comprising a vacuum bottle body used to provide a vacuum testing environment for a sample;

[0007] The vacuum bottle is equipped with a cryogenic system and a superconducting magnet system. The superconducting magnet system includes a superconducting magnet coil. The cryogenic system and the superconducting magnet coil work together to couple the magnetic field with the cryogenic environment under the vacuum test environment.

[0008] The cryogenic system includes a refrigerator and a cooling column. The primary and secondary cold heads of the refrigerator are connected to the first and second cold plates respectively through cooling materials.

[0009] The cold conducting column is connected with a temperature control device, and the temperature control device comprises a thermal switch, which is used to switch the cold conducting temperature of the first cold plate to the sample and the cold conducting temperature of the second cold plate to the sample.

[0010] The cold conducting column is connected with a heating rod, and the cold conducting column is sleeved with a third cold shield, which is used to isolate the temperature zones of the cold conducting column.

[0011] Preferably, the first cold plate is connected with a first cold shield, the second cold plate is connected with a second cold shield, the first cold shield is sleeved outside the second cold shield, the second cold shield is sleeved outside the superconducting magnet coil, and the superconducting magnet coil is sleeved outside the third cold shield.

[0012] Preferably, the sample, the cold conducting column, the third cold shield, the superconducting magnet coil, the second cold shield and the first cold shield are coaxially arranged.

[0013] Preferably, the temperature control device comprises a screw lifter, which is fixedly installed on a vacuum bottle body, and is provided with a lifting rod connected with a bellows and a thermal switch.

[0014] Preferably, the thermal switch is provided with a second temperature sensing layer, a trigger layer and a first temperature sensing layer from top to bottom, wherein the trigger layer is fixedly installed at the top end of the lifting rod.

[0015] Preferably, the second temperature sensing layer is fixedly installed at the second cold plate, and the first temperature sensing layer is fixedly installed at the first cold plate.

[0016] Preferably, a soft connection is arranged between the trigger layer and the cold conducting column, and the trigger layer is connected with the cold conducting column through the soft connection.

[0017] Preferably, the soft connection is a woven tape made of oxygen-free copper material.

[0018] Preferably, the cold conducting column is a hollow and through column structure, a support column is arranged in the central passage of the cold conducting column, the bottom of the cold conducting column is fixedly connected with the support column, and a sample stage is fixedly arranged at the top of the support column, and the cold conducting column and the sample stage abut each other for cold conducting.

[0019] An operating method of a variable temperature magnetic field probe test platform, comprising:

[0020] Fixing the sample on the sample stage and vacuumizing the vacuum bottle body;

[0021] Starting the refrigerator to cool the vacuum test environment, and the superconducting magnet coil becomes superconducting state after being cooled to low temperature test condition, and the superconducting magnet coil is supplied with current to generate a set magnetic field.

[0022] A test temperature is preset, a temperature adjusting device is adjusted based on the preset temperature, and the cold energy of the first cold plate or the second cold plate is transmitted to the sample through a thermal switch;

[0023] The temperature of the sample after cooling is compensated by the heating rod until the temperature of the sample is the same as the preset test temperature.

[0024] The present application has the following advantages:

[0025] (1) In the present application, the cooling temperature of the sample is switched by the thermal switch of the temperature adjusting device according to the required test temperature of the sample. Based on the cooling temperature, the sample temperature is precisely adjusted by the heating rod until the sample temperature reaches the test temperature, so that the control precision of the sample temperature is higher, the temperature span is larger, and the material property test range of the sample to be tested is further improved, avoiding the limitation of the sample by a single test temperature.

[0026] (2) In the present application, after the vacuum bottle in the Dewar is evacuated, the cryocooler in the low-temperature system cools the vacuum bottle, at the same time, the current passes through the superconducting magnet coil, and the low-temperature system cools the superconducting magnet coil to the preset low-temperature test condition, then the superconducting magnet coil becomes a superconducting state, the current generates a uniform and stable set magnetic field, and acts on the sample. Compared with the electromagnet, the magnetic field generated by the superconducting magnet coil is more uniform and stable, and the magnetic field strength is also much higher than that of the electromagnet.

[0027] (3) The superconducting magnet coil has zero resistance characteristics at low temperature. When the current is excited, the current can flow continuously in the superconducting magnet coil without generating heat in the superconducting state. Unlike traditional electromagnets, electromagnets will generate heat due to resistance effect when current is applied, resulting in temperature rise, and additional cooling means is needed to maintain the low-temperature environment. The current of the superconducting magnet coil does not consume energy, and there is no need to consider the heating problem caused by the electromagnet. This makes it possible to generate a stable magnetic field in a low-temperature environment without destroying the low-temperature condition, and there is no need to set other auxiliary structures to maintain the low-temperature environment, realizing the coexistence of low-temperature environment and magnetic field environment.

[0028] (4) In the present application, the magnetic field at the sample is continuously changed from 0-3.5T by controlling the current and can be stable in this range, and the superconducting magnet system can provide wider selectable test conditions.

[0029] (5) In the present application, the third cold screen can isolate the cold lead column below the sample into temperature zones to isolate heat radiation. The heat generated by the heating rod is isolated in the third cold screen, avoiding the heat from being emitted to the first cold screen and the second cold screen to affect the low-temperature environment. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1A structural schematic diagram of a variable-temperature magnetic field probe test platform provided by the present application;

[0031] Figure 2 A sectional view of a variable-temperature magnetic field probe test platform provided by the present application;

[0032] Figure 3 A variable-temperature magnetic field probe test platform provided by the present application; Figure 2 An enlarged view of A in FIG. 1;

[0033] Figure 4 An enlarged view of B in FIG. 1; Figure 3 An enlarged view of B in FIG. 1;

[0034] Figure 5 A flowchart of an operation method of a variable-temperature magnetic field probe test platform provided by the present application.

[0035] BRIEF DESCRIPTION OF THE DRAWINGS

[0036] 1, Dewar; 11, vacuum bottle body; 12, bottle cap; 2, low-temperature system; 21, refrigerator; 22, second cold shield; 23, first cold shield; 24, third cold shield; 25, soft connection; 26, cold lead column; 27, sample stage; 28, support column; 29, second cold plate; 210, first cold plate; 3, superconducting magnet system; 31, superconducting magnet coil; 32, skeleton; 4, three-dimensional probe arm; 5, magneto-optical imaging microscope system; 6, temperature control device; 61, lifting rod; 62, knob; 63, bellows; 64, trigger layer; 65, first temperature sensing layer; 66, second temperature sensing layer. DETAILED DESCRIPTION

[0037] The specific embodiments of the present application are described in detail below, but it should be understood that the scope of protection of the present application is not limited by the specific embodiments.

[0038] The prior art uses electromagnets to provide a magnetic field, which does not fully meet the testing needs of semiconductor materials. The field strength and magnetic field uniformity are limited by electromagnets, which are insufficient to simulate the actual use environment of semiconductor materials. Moreover, the cooling capacity provided by the refrigerator is generally transferred to the sample through a first cold head and a second cold head. The temperatures of the first cold head and the second cold head are different, and in general, the temperature of the first cold head is higher than that of the second cold head. This makes the cooling temperature of the sample switch between these two temperature values, and other temperature values cannot be adjusted.

[0039] Moreover, the magnetism of electromagnets will change significantly in a low-temperature environment (such as 4K-40K). The magnetism of ferromagnetic materials will increase, and paramagnetic materials will also exhibit spin freezing. These changes will all affect the experimental results. In addition, electromagnets will generate heat due to the resistance effect when an electric current is applied, which will cause the temperature to rise and thus destroy the low-temperature environment.

[0040] For example,Figure 1 As shown, the present invention provides a variable-temperature magnetic field probe testing platform, comprising:

[0041] Dewar 1 includes a vacuum bottle 11 and a support, with the vacuum bottle 11 fixed to the support. The vacuum bottle 11 is connected to a molecular pump unit, which can evacuate the vacuum bottle 11 to provide a vacuum testing environment for the sample and also to provide conditions for cooling the superconducting magnet coil 31.

[0042] like Figures 2-3 As shown, a cryogenic system 2 and a superconducting magnet system 3 are installed inside the vacuum chamber 11. The cryogenic system 2 includes a refrigerator 21, which is mounted on a bracket. The refrigerator 21 uses helium as a refrigerant, working in conjunction with a compressor-water chiller to cool the primary cold head to 40K and the secondary cold head to 4K. The cooling effect transferred through the primary or secondary cold head cools the vacuum testing environment. The superconducting magnet system 3 includes a superconducting magnet coil 31, which is fixed to a frame 32. The cryogenic system 2 and the superconducting magnet coil 31 work together to couple the magnetic field with the cryogenic environment under vacuum testing conditions.

[0043] The superconducting magnet coil 31 is made of NbTi superconducting wire wound into a solenoid shape. This NbTi superconducting wire becomes superconducting below the critical current, critical field strength, and critical temperature, causing the applied current to generate a predetermined magnetic field. In use, the current from an external DC constant current source passes through a high-temperature superconducting current lead to the superconducting magnet coil 31. After the cryogenic system 2 cools the superconducting magnet coil 31 to the preset low-temperature test conditions, the superconducting magnet coil 31 becomes superconducting, and the current generates a uniform and stable predetermined magnetic field. In this embodiment, by controlling the current, the magnetic field at the sample can be continuously varied from 0 to 3.5T and stabilized within this range. The superconducting magnet system 3 can provide a wider range of selectable test conditions.

[0044] Specifically, the superconducting magnet coil 31 exhibits zero resistance at low temperatures, meaning that once current is activated, it can flow continuously within the coil without generating heat (in the superconducting state). This differs from conventional electromagnets, which generate heat due to resistance when current is applied, leading to a temperature increase and requiring additional cooling to maintain the low-temperature environment. Because the current in the superconducting magnet coil 31 does not lose energy, there is no need to consider the heat generated by the electromagnet. This allows for the generation of a stable magnetic field at low temperatures without disrupting the cryogenic conditions, and eliminates the need for additional auxiliary structures to maintain the cryogenic environment. Therefore, the superconducting magnet coil 31 can maintain a stronger magnetic field at low temperatures and has advantages in both magnetic field strength and stability.

[0045] Moreover, the superconducting magnet coil 31 can generate a stronger magnetic field with less current. Because the superconducting magnet coil 31 has no resistive losses, it can carry a greater current density and thus generate a stronger magnetic field. Using the superconducting magnet coil 31 in the superconducting magnet system 3 at low temperature can achieve a higher magnetic field strength than a conventional electromagnet without increasing the current or current density. While a conventional electromagnet needs to maintain a constant current and voltage at low temperature, the resistive changes due to temperature can affect the uniformity and strength of the magnetic field, which can be avoided by the superconducting magnet coil 31.

[0046] In addition, the superconducting magnet coil 31 is made of NbTi superconducting wire, which is a high-purity alloy and a low-temperature superconducting material. The mechanical properties of this material are more stable at low temperatures, and it is not easy to become brittle or crack. Therefore, the superconducting magnet coil 31 performs more reliably at low temperatures, while a conventional electromagnet can be affected by material shrinkage and brittleness at low temperatures, which can cause failure or performance degradation. The superconducting magnet coil 31 can stably work in a superconducting state in a low-temperature range below 5K, and in this embodiment, its superconducting performance is generally maintained at a low temperature of 4K. Once the temperature of a conventional electromagnet is too low, especially close to the temperature of liquid helium, the electrical conductivity and performance of the material will often decrease significantly.

[0047] As shown in FIG. 1, the superconducting magnet system 3 includes a superconducting magnet coil 31, a first cold plate 210, a second cold plate 29, a first cold shield 23, a second cold shield 22, a sample stage 27, a support column 28, a cooling column 26, a cryostat 21, and a vacuum bottle 11. Figure 3 The first cold plate 210 and the second cold plate 29 are connected to the first cold head and the second cold head of the cryostat 21 through a cooling material, respectively. The first cold plate 210 is connected to the first cold shield 23, and the second cold plate 29 is connected to the second cold shield 22. The first cold shield 23 and the second cold shield 22 are provided to prevent heat from being directly radiated from 300K (i.e., room temperature) to the surface of the superconducting magnet coil 31. The second cold shield 22 provides a working temperature for the superconducting magnet coil 31 arranged inside the second cold shield 22 by stabilizing the internal temperature at 4K through the transmission of cold energy from the second cold head. The second cold shield 22 is provided with a cooling column 26. The cooling column 26 is a hollow and through column structure, and a support column 28 is arranged in the center channel of the cooling column 26. The bottom of the cooling column 26 is fixedly connected to the support column 28, and the top of the support column 28 is fixedly connected to the sample stage 27 for placing a sample. The cooling column 26 and the sample stage 27 abut for cooling. The second cold shield 22 and the support column 28 are fixed in the first cold shield 23 through a support column or a support seat, and the first cold shield 23 is fixed to the vacuum bottle 11 through a support column.

[0048] The cold lead 26 is connected to a heating rod, which includes but is not limited to a resistance heating rod, a ceramic heating rod, a carbon fiber heating rod, and preferably a vacuum heating rod. In some embodiments, the heating rod can also be arranged on the sample stage 27 to directly adjust the temperature of the sample, which is an alternative solution of the present application and falls within the protection scope of the present application. The cold lead 26 is further sleeved with a third cold shield 24, which isolates the cold lead 26 in temperature zones to achieve thermal radiation isolation and prevent the heat generated by the heating rod from radiating to the surface of the superconducting magnet coil 31. The heat generated by the heating rod is isolated in the third cold shield 24 to avoid heat dissipation to the first cold shield 23 and the second cold shield 22, thereby affecting the low-temperature environment.

[0049] In the present application, the heating rod can further adjust the cooling temperature of the sample based on the cooling temperature of the first cold plate 210 or the second cold plate 29, so that the cooling temperature of the sample can be switched between the two temperature values (the temperature values of the two cooling temperatures are provided by the first cold plate 210 and the second cold plate 29) while the heating rod is cooperatively adjusted based on the two temperature values to enable the cooling temperature of the sample to reach other temperature values, thereby expanding the material property test range of the sample.

[0050] The cold lead 26 is made of G10 material, which has low thermal conductivity, and the length of the cold lead 26 is as long as possible. The long cold lead 26 can avoid rapid transfer of cold to the sample. Rapid cooling of the semiconductor material sample can cause inconsistent temperature changes in different parts of the sample, resulting in thermal stress, which can cause changes in the crystal structure and even induce micro-cracks. Such structural changes can affect the electrical properties (such as sudden changes in the band gap, carrier mobility, and other properties of semiconductor materials), optical properties, or other properties of the material, resulting in large deviations in test results. Moreover, for some precision measurements such as current-voltage characteristics and Hall effect, the stability of temperature control is crucial. Rapid cooling of the sample can cause uneven temperature, which in turn affects the performance of the semiconductor material. For some superconducting material samples, in addition to the problem of thermal stress, the superconducting state of the sample usually changes below the critical temperature, and the superconducting property gradually increases with the decrease of temperature. If the cooling speed is too fast, the temperature change of the material will also be too drastic, causing it to not smoothly enter the superconducting state. This unstable cooling process also causes the sample to be unable to maintain constant superconducting properties near the critical temperature, thereby affecting the accuracy of performance testing.

[0051] It should be noted that the first cold screen 23 is arranged outside the second cold screen 22, the second cold screen 22 is arranged outside the superconducting magnet coil 31, the superconducting magnet coil 31 is arranged outside the third cold screen 24, the third cold screen 24 is arranged outside the cold column 26, and the sample, the cold column 26, the third cold screen 24, the superconducting magnet coil 31, the first cold screen 23 and the second cold screen 22 are coaxially arranged, so that the magnetic field received by the sample is more uniform and the cooling process is more stable.

[0052] As shown in Figures 3-4 The cold column 26 is connected to the temperature control device 6, and the temperature control device 6 includes a screw lift fixedly installed on the vacuum bottle body 11. The screw lift is provided with a lifting rod 61 and a knob 62 located outside the vacuum bottle body 11. The lifting rod 61 is driven to lift by rotating the knob 62, and the corrugated pipe 63 connected to the lifting rod 61 also expands and contracts with the lifting of the lifting rod 61. The lifting rod 61 is also connected to a thermal switch for switching the cooling temperature of the sample by the first cold plate 210 and the cooling temperature of the sample by the second cold plate 29.

[0053] Specifically, the thermal switch is provided with a second temperature sensing layer 66, a trigger layer 64 and a first temperature sensing layer 65 from top to bottom. The trigger layer 64 is fixedly installed at the top end of the lifting rod 61, and a soft connection 25 is arranged between the trigger layer 64 and the cold column 26, and the two are connected through the soft connection 25. The soft connection 25 is a woven tape made of oxygen-free copper material, which has high RRR value and high thermal conductivity, so as to improve the transmission efficiency of cold energy.

[0054] Further, the second temperature sensing layer 66 is fixedly installed at the second cold plate 29, and the first temperature sensing layer 65 is fixedly installed at the first cold plate 210. When the trigger layer 64 moves upward and contacts the second temperature sensing layer 66, the cold energy provided by the secondary cold head is transmitted from the second cold plate 29 to the second temperature sensing layer 66, and then from the second temperature sensing layer 66 to the trigger layer 64, and then from the trigger layer 64 to the cold column 26 through the soft connection 25, and finally the sample is cooled to 4K. Correspondingly, when the trigger layer 64 moves downward and contacts the first temperature sensing layer 65, the cold energy provided by the primary cold head is sequentially transmitted through the first cold plate 210, the first temperature sensing layer 65, the trigger layer 64, the soft connection 25, the cold column 26, and finally the sample is cooled to 40K. By switching the contact of the trigger layer 64 to the first temperature sensing layer 65 and the second temperature sensing layer 66, the effect of variable temperature cooling of the sample can be achieved.

[0055] As shown in Figure 1As shown, the variable-temperature magnetic field probe test platform further comprises a plurality of three-dimensional probe arms 4 arranged around the sample and a magneto-optical imaging microscope system 5 located above the sample. In this embodiment, five three-dimensional probe arms 4 are provided, and the three-dimensional probe arms 4 are located outside the vacuum bottle body 11. The probes assembled by the three-dimensional probe arms 4 pass through the vacuum bottle body 11 and the first cold shield 23 to apply an electrical signal to the sample needle on the sample table 27 to test the electrical properties of the sample. The magneto-optical imaging microscope system 5 can apply polarized light to the sample. The polarized light enters the fixed sample on the sample table 27 through the window in the center of the bottle cap 12. Under the cooperation of the magneto-optical Kerr microscope and the magneto-optical film, the magnetic domain phenomenon of the sample can be observed. In addition, the magneto-optical imaging microscope system 5 is installed through a support, and the magneto-optical imaging microscope system 5 can be moved. This is a more mature prior art, so it will not be described here.

[0056] In this application, after the Dewar 1 is evacuated, the cryogenic refrigerator 21 cools the vacuum bottle body 11, and at the same time, the superconducting magnet coil 31 applies a uniform strong magnetic field to the sample to realize the coexistence of low-temperature environment and magnetic field environment. By rotating the knob 62, the first cold plate 210 or the second cold plate 29 is switched to the sample through the thermal switch according to the required test temperature of the sample. Based on the cold temperature, the sample temperature is precisely adjusted by using the heating rod until the sample temperature reaches the test temperature, so that the control accuracy of the sample temperature is higher and the temperature span is larger, further improving the material property test range of the sample to be tested, avoiding the limitation of the sample by a single test temperature. When the sample reaches the test temperature, the electrical properties, optical properties and other properties of the sample are tested.

[0057] In an embodiment, as shown in the variable-temperature magnetic field probe test platform provided by the application, Figures 1-5 The operation method of the variable-temperature magnetic field probe test platform comprises the following steps:

[0058] S1, the sample is fixed on the sample table 27 by low-temperature adhesive tape, and the vacuum bottle body 11 is evacuated by the molecular pump unit.

[0059] S2, the cryogenic refrigerator 21 is started to cool the vacuum test environment, the current from the external direct-current constant-current source passes through the high-temperature superconducting current lead to the superconducting magnet coil 31, and after the low-temperature system 2 cools the superconducting magnet coil 31 to the preset low-temperature test condition, the superconducting magnet coil 31 becomes a superconducting state, and the current generates a set magnetic field.

[0060] S3, a test temperature is preset, the temperature adjusting device 6 is adjusted based on the preset temperature, and the cold quantity of the first cold plate 210 or the second cold plate 29 is transmitted to the sample through the thermal switch.

[0061] Specifically, according to the preset test temperature, the knob 62 is rotated to make the lifting rod 61 rise or fall. When the preset test temperature is close to 4K, the lifting rod 61 rises to make the trigger layer 64 move upward until it is in contact with the second temperature sensing layer 66. When the preset test temperature is close to 40K, the lifting rod 61 falls to make the trigger layer 64 move downward until it is in contact with the first temperature sensing layer 65.

[0062] When the trigger layer 64 moves upward and is in contact with the second temperature sensing layer 66, the cold energy provided by the secondary cold head is transmitted from the second cold plate 29 to the second temperature sensing layer 66, then from the second temperature sensing layer 66 to the trigger layer 64, and then from the trigger layer 64 to the cold lead column 26 through the soft connection 25, and finally the sample is cooled to 4K. Correspondingly, when the trigger layer 64 moves downward and is in contact with the first temperature sensing layer 65, the cold energy provided by the primary cold head is transmitted from the first cold plate 210 to the first temperature sensing layer 65, then from the first temperature sensing layer 65 to the trigger layer 64, and then from the trigger layer 64 to the cold lead column 26 through the soft connection 25, and finally the sample is cooled to 40K.

[0063] S4, temperature compensation is performed on the cooled sample by the heating rod until the temperature of the sample is the same as the preset test temperature, and material property testing is performed on the sample.

[0064] The heating rod can further adjust the cooling temperature of the sample based on the first cold plate 210 or the second cold plate 29, so that the cooling temperature of the sample can be switched between the two temperature values of 4K and 40K, and the heating rod can be cooperatively adjusted based on the two temperature values, so that the cooling temperature of the sample can accurately reach the preset test temperature.

[0065] When the material properties of the sample are tested, the probe of the three-dimensional probe arm 4 is inserted through the vacuum bottle body 11 and the first cold screen 23 to apply an electrical signal to the sample on the sample table 27 to test the electrical properties of the sample.

[0066] The sample is subjected to polarized light by the magneto-optical imaging microscope system 5, the polarized light is injected into the fixed sample on the sample table 27 through the vacuum observation window in the center of the bottle cap 12, and the magnetic domain phenomenon of the sample can be observed under the cooperation of the magneto-optical Kerr microscope and the magneto-optical film.

[0067] The specific test can be adjusted according to actual needs, for example, the three-dimensional probe arm 4 can not be used when some samples do not need to test the electrical properties.

[0068] The above disclosure is only a few specific embodiments of the present application, but the embodiments of the present application are not limited thereto, and any changes that can be thought of by those skilled in the art shall fall within the protection scope of the present application.

Claims

1. A variable-temperature magnetic field probe testing platform, characterized in that, include: Dewar (1), the Dewar (1) includes a vacuum bottle (11) for providing a vacuum testing environment for the sample; The vacuum bottle (11) is equipped with a cryogenic system (2) and a superconducting magnet system (3). The superconducting magnet system (3) includes a superconducting magnet coil (31). The cryogenic system (2) and the superconducting magnet coil (31) work together to couple the magnetic field with the cryogenic environment under the vacuum test environment. The low-temperature system (2) includes a refrigerator (21) and a cooling column (26). The first-stage cold head and the second-stage cold head of the refrigerator (21) are connected to the first cold plate (210) and the second cold plate (29) respectively through the cooling material. The cooling column (26) is connected to the temperature control device (6), which includes a thermal switch. The thermal switch is used to switch the cooling temperature of the first cold plate (210) on the sample and the cooling temperature of the second cold plate (29) on the sample. The cooling column (26) is connected to the heating rod, and the cooling column (26) is fitted with a third cooling screen (24), which isolates the cooling column (26) in temperature zones.

2. The variable-temperature magnetic field probe testing platform as described in claim 1, characterized in that, The first cold plate (210) is connected to the first cold screen (23), the second cold plate (29) is connected to the second cold screen (22), and the first cold screen (23) is sleeved outside the second cold screen (22), the second cold screen (22) is sleeved outside the superconducting magnet coil (31), and the superconducting magnet coil (31) is sleeved outside the third cold screen (24).

3. The variable-temperature magnetic field probe testing platform as described in claim 2, characterized in that, The sample, the cooling column (26), the third cooling screen (24), the superconducting magnet coil (31), the second cooling screen (22) and the first cooling screen (23) are all coaxially arranged.

4. The variable-temperature magnetic field probe testing platform as described in claim 1, characterized in that, The temperature control device (6) includes a screw jack, which is fixedly installed on the vacuum bottle body (11). The screw jack is provided with a lifting rod (61), which is connected to a bellows (63) and is connected to the thermal switch.

5. The variable-temperature magnetic field probe testing platform as described in claim 4, characterized in that, The thermal switch is provided with a second temperature sensing layer (66), a trigger layer (64) and a first temperature sensing layer (65) from top to bottom, wherein the trigger layer (64) is fixedly installed on the top of the lifting rod (61).

6. The variable-temperature magnetic field probe testing platform as described in claim 5, characterized in that, The second temperature-sensing layer (66) is fixedly installed at the second cold plate (29), and the first temperature-sensing layer (65) is fixedly installed at the first cold plate (210).

7. The variable-temperature magnetic field probe testing platform as described in claim 5, characterized in that, A flexible connection (25) is provided between the trigger layer (64) and the cooling column (26), and they are connected through the flexible connection (25).

8. The variable-temperature magnetic field probe testing platform as described in claim 7, characterized in that, The flexible connector (25) is a braided strip made of oxygen-free copper material.

9. The variable-temperature magnetic field probe testing platform as described in claim 1, characterized in that, The cooling column (26) is a hollow and through column structure. A support column (28) is provided in the central channel of the cooling column (26). The bottom of the cooling column (26) is fixedly connected to the support column (28). A sample stage (27) is fixed to the top of the support column (28). The cooling column (26) and the sample stage (27) abut against each other for cooling.

10. A method of operating the variable-temperature magnetic field probe testing platform according to any one of claims 1-9, characterized in that, include: Fix the sample on the sample stage (27) and evacuate the vacuum bottle (11); Start the refrigerator (21) to cool the vacuum test environment. After the superconducting magnet coil (31) is cooled to the low temperature test condition, it becomes superconducting. Current is passed into the superconducting magnet coil (31) to generate the set magnetic field. A test temperature is preset, and based on the preset temperature regulation and control device (6), the cold energy of the first cold plate (210) or the second cold plate (29) is transferred to the sample through a thermal switch; Temperature compensation is performed on the cooled sample using a heating rod until the sample temperature is the same as the preset test temperature.

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