CN203535204U - Sample rod for contactless low-temperature magneto-transport tests - Google Patents

Abstract

The utility model discloses a non-contact low-temperature magnetic transport test sample rod, which is used for microwave measurement of the electrical properties of solid materials under a deep low-temperature strong magnetic field. The sample rod is composed of head-top box, waveguide, lead pipe, coaxial cable and adapter, test lead and socket, bracket plate, bottom fixing frame and resonance cavity, etc. Its main feature is that the waveguide and coaxial cable are introduced into the In the sample rod, the waveguide guides the microwave into the harmonic cavity where the sample can be placed, and the coaxial cable receives the reflected microwave, so as to realize the microwave measurement of the electrical properties of the solid material. The waveguide and the lead tube are made of titanium material with high strength and low thermal conductivity, which realizes the stability of the sample temperature at extremely low temperature. The system provides a powerful research tool for microwave measurement of electrical properties of solid materials in deep low temperature and strong magnetic fields.

Description

Sample Holder for Non-Contact Low-Temperature Magnetic Transport Testing

technical field

This patent relates to a sample rod for microwave detection of electrical properties of solid materials, specifically to a sample rod for non-contact microwave measurement under deep low temperature and strong magnetic field, for in situ research on electrical transport quantum under microwave irradiation effect and electron spin resonance etc.

Background technique

The study of the properties of solid materials under extreme conditions is an important content in the field of condensed matter physics. Quantum effects in solid materials become significant at extremely low temperatures and strong magnetic fields. For example, there are quantum corrections to the classical conductivity of solid materials at deep low temperatures, manifested as weak local effects and weak antilocal effects, magnetoresistance oscillations, and quantum Hall effects, etc., which involve electron spin characteristics and self- spin-orbit coupling and other fundamental quantum physics effects. The quantum properties related to electron spin in solid materials can provide the principle basis of device fabrication and manipulation for a new generation of micro-nano electronic devices - spintronics devices, so it has important research value.

The traditional low-temperature magnetic transport test sample rod adopts a contact electrical transport measurement method, that is, by applying a voltage (or current) to the sample and then measuring the required current (or voltage), it is necessary to make electrodes on the sample , so it is a lossy measurement method. The traditional low-temperature magnetic transport sample rod that introduces microwave irradiation only introduces microwave irradiation at the same time as the electrical transport measurement, using the heating modulation effect of microwaves, and still has contact measurement and measures the indirect response of microwaves. , that is, the microwave response is transformed into a physical quantity that has nothing to do with the microwave itself. For some solid materials, due to their own material properties or sample size, the fabrication of electrodes is very difficult. According to the interaction between microwave and solid material, the non-contact and non-destructive measurement of solid material can be realized by irradiating the sample with microwave and measuring the direct response to microwave. Based on the superiority of microwave measurement, this patent designs a sample rod for microwave measurement under deep low temperature and strong magnetic field. The waveguide and coaxial cable are introduced into the sample rod to realize the continuous change of microwave frequency in a large range, which can realize The in-situ microwave measurement of the electrical properties of solid materials provides a powerful research tool for the study of magnetic transport testing and electron spin resonance under extremely low temperature, strong magnetic field and microwave irradiation.

Contents of the invention

The purpose of this patent is to provide a sample rod for non-contact low-temperature magnetic transport testing, which solves the problem of difficulty in making sample electrodes in traditional electrical transport testing.

This patent introduces a microwave measurement method into the traditional magnetic transport test of solid materials under extremely low temperature and strong magnetic field, so as to study the magnetic transport properties of solid materials under microwave irradiation in situ, such as conductance quantum correction and spin correlation characteristics. microwave response. The microwave irradiation includes continuous and pulsed microwave signals of different power and frequency, and the microwave test includes the magnetic input of materials such as resistivity and Hall coefficient at different microwave frequencies, powers, magnetic fields, and temperatures. Contactless microwave measurements of this nature.

This patent introduces a waveguide and a coaxial cable inside the sample rod, which can introduce microwaves into the sample, and realize the in-situ research on the electrical transport characteristics and spin characteristics under microwave irradiation. Measurements provide an effective tool.

The technical scheme of this patent is as follows:

The sample rod 200 includes a head-top box 201, a head-top box cover 202, a protective cover 203, a fixed hinge 204, a fixed hinge 205, a frequency multiplier 206, a rectangular-circle converter 207, a coaxial waveguide conversion head 208, a coaxial cable adapter 209, Test line adapter A210, test line adapter B211, coaxial waveguide connection line 212, coaxial cable 213, test lead A214, test lead B215, sealing O-ring 216, sealing sleeve flange 217, waveguide 218, 4 Root lead tube 219, 5 support discs 220, bottom fixing frame 221, resonant cavity 222, the basic structure is shown in accompanying drawing 1.

Its overall structure is as follows: the head-top box 201 is welded with the protective cover 203, the waveguide 218, and the four lead pipes 219, and the waveguide 218 and the four lead pipes 219 are fixed together by five support discs 220 and the bottom fixing frame 221, and the resonance The cavity 222 is connected to the bottom fixing frame 221 through screws, the waveguide 218 is fixed on the central round holes of the five bracket discs 220 and the bottom fixing bracket 221, and the four lead tubes 219 are fixed on the five bracket discs 220 and the bottom fixed On the edge symmetrical round hole of frame 221; The diameter of head-top box cover 202 matches that of head-top box 201, seals with the head-top box 201 through sealing O-ring 216 with fixed hinge 204 and _fixed hinge 205; Coaxial cable 213, test Lead A214 and test lead B215, one end of which enters the sample at the bottom of the sample rod through any one of the four lead tubes 219, and the other end is respectively connected to the coaxial cable adapter 209, the test line adapter A210, and the test line adapter B211 is connected; the sealing O-ring 216 seals between the overhead box 201 and the overhead box cover 202 , and the sealing sleeve flange 217 seals the top interface between the protective cover 203 and the cryogenic Dewar 301 .

The head-top box 201 is made of non-magnetic stainless steel, its top is open, its bottom is sealed and welded to the top of the protective cover 203 , and is sealed and welded to the waveguide 218 and the lead tube 219 . A semicircular groove is left on the top section of the side wall to place a sealing O-ring 216 so as to seal with the head box cover 202 . Horizontal support bars are respectively welded on both sides of the top of the side wall to connect the fixed hinge 204 and the fixed hinge 205 respectively. There are four circular holes on the side wall, which are respectively used to place the coaxial waveguide adapter 208, the coaxial cable adapter 209, the test line adapter A210 and the test line adapter B211. Its internal bottom surface is welded with the rectangle converter 207. A frequency multiplier 206 can be placed inside it, and it can be connected with the rectangular converter 207 with screws.

The overhead box cover 202 is made of non-magnetic stainless steel and is used to seal the overhead box 201 . Fixed hinge 205 is welded on its surface.

The protective cover 203 is made of non-magnetic stainless steel, its top is sealed and welded to the head-top box 201 , and its bottom and the top interface of the cryogenic Dewar 301 can be sealed through the sealing sleeve flange 217 .

The fixed hinge 204 is made of non-magnetic stainless steel, and can be connected with the horizontal support bar on one side of the overhead box 201 by a long screw. It itself has a long screw with a butterfly handle, which is used to fix the hinge 204 so that the overhead box cover 202 and the overhead box 201 are sealed.

The fixed hinge 205 is made of non-magnetic stainless steel, which is welded on the surface of the overhead box cover 202, and can be connected with the horizontal support bar on the overhead box 201 side by a long screw. It itself has a long screw with a butterfly handle, which is used to fix the hinge 205 so that the overhead box cover 202 and the overhead box 201 are sealed.

The frequency multiplier 206 is used to extend the microwave frequency range, and can be connected to the rectangular converter 207 through screws.

The rectangle converter 207 is used to change the shape of the waveguide opening, so that the microwave enters the circular waveguide opening of the waveguide 218 from the rectangular waveguide opening of the frequency multiplier 206 . Its bottom is welded to the inner bottom surface of the head-top box 201, and the head can be connected with the frequency multiplier 206 through screws.

The coaxial waveguide conversion head 208 is installed on the side wall of the head-top box 201, the outer end is an external coaxial cable interface, and the inner end is connected with the coaxial waveguide connection line 212, thereby realizing the conversion and connection of microwave signals from the external coaxial cable to the waveguide. The inner and outer ends of the coaxial waveguide conversion head 208 are airtight.

The coaxial cable adapter 209 is installed on the side wall of the head-top box 201, the outer end is an outer coaxial cable interface, and the inner end is connected with the coaxial cable 213 to realize the connection of the microwave signal between the coaxial cable 108 and the outer coaxial cable. The inner and outer ends of the coaxial cable adapter 209 are airtight.

The test line adapter A210 is installed on the side wall of the head-top box 201, the outer end is an A-type shielded cable interface, and the inner end is connected to the test lead A214. The test line adapter A210 is airtight between the inner and outer ends.

The test line adapter B211 is installed on the side wall of the head-top box 201, the outer end is a B-type shielded cable interface, and the inner end is connected to the test lead B215. The test line adapter B211 is airtight between the inner and outer ends.

The coaxial waveguide connection line 212 is located inside the head-top box 201 and is used to connect the inner end of the coaxial waveguide conversion head 208 and the frequency multiplier 206 .

The coaxial cable 213 is located inside the sample rod 200 for receiving microwaves reflected at the bottom of the sample rod 200 . One end thereof is connected to the coaxial cable adapter 209 , and the other end extends into the bottom of the sample rod 200 through any one of the four lead tubes 219 .

The test lead A214 is located inside the sample rod 200 and is a 19-core metal wire, which is used to connect the electrode of the sample and the external detection circuit during contact measurement. One end thereof is connected to the test line adapter A210 , and the other end extends into the bottom of the sample rod 200 through any one of the four lead tubes 219 .

The test lead B215 is located inside the sample rod 200 and is a 21-core metal wire, which is used to connect the electrode of the sample and the external detection circuit during contact measurement. One end thereof is connected to the test line adapter B211 , and the other end extends into the bottom of the sample rod 200 through any one of the four lead tubes 219 .

The waveguide 218 is used to introduce microwaves to the bottom of the sample rod 200 . Its top is welded to the bottom surface of the head-top box 201 . Its bottom end extends into the bottom of the sample rod 200 and is facing the resonant cavity 222 , but not in contact with the resonant cavity 222 . The waveguide 218 is fixed together with the four lead pipes 219 through five support discs 220 , and its bottom end is inserted into the central circular hole of the bottom fixing frame 221 . The waveguide 218 is made of a titanium tube with low thermal conductivity, so as to prevent it from conducting heat to the resonant cavity 222 in an extremely low temperature environment, so that the temperature of the sample in the resonant cavity 222 cannot be stabilized at an extremely low temperature.

Four lead tubes 219 are used to lead coaxial cables 213 , test leads A 214 , test leads B 215 or other types of leads (such as optical fibers) to the bottom of the sample rod 200 . Its top is welded to the bottom surface of the head-top box 201 . Its bottom end extends into the bottom of the sample rod 200 . The four lead pipes 219 are fixed together with the waveguide 218 through five support discs 220 , and their bottom ends are inserted into the outer circular holes of the bottom fixing frame 221 . The four lead tubes 219 are made of titanium tubes with low thermal conductivity, so as to prevent them from conducting heat to the resonant cavity 222 in an extremely low temperature environment and causing the temperature of the sample in the resonant cavity 222 to be unable to stabilize at an extremely low temperature.

Five support discs 220 are used to fix the waveguide 218 and four lead tubes 219. The five support discs 220 are provided with a central large circular hole and four symmetrical small circular holes near the edge, and two holes are left on the edge. There are two side grooves perpendicular to each other in order to meet the needs of pumping and reducing pressure in the sample rod during decompression and cooling.

The bottom fixing frame 221 is used for fixing the bottoms of the waveguide 218 and the four lead tubes 219 . There is a central circular hole and four symmetrical circular holes near the edge, through which the waveguide 218 and four lead tubes 219 pass through. There are also two arms extending on its symmetrical edge for connecting with the resonant cavity 222 .

The resonant cavity 222 is in the shape of a basket for placing samples and responding to microwaves. There are two arms extending from its symmetrical edge, which can be connected with the two arms of the bottom fixing frame 221 through screws.

The use method and process of this patent are as follows: first, place the sample rod 200 flat on the platform, and use elastic sponges to raise its two ends respectively to keep the sample rod body (ie, the part of the waveguide 218 and the four lead tubes 219 ) level. Place the sample inside the resonant cavity 222 and fix it, then connect and fix the resonant cavity 222 and the bottom fixing frame 221 with screws, and ensure that the central axis of the resonant cavity 222 coincides with the central axis of the waveguide 218. Close the head-top box cover 202 of the sample rod 200 with the head-top box 201 through the fixed hinge 204 and the fixed hinge 205 (if it is already closed, this step can be omitted). Lift the prepared sample rod 200, move it near the top interface of the low-temperature Dewar 301, then erect it, and slowly insert it from the top interface of the low-temperature Dewar 301 (this step can be assisted by a lifting mechanism ), until the protective cover 203 of the sample rod 200 is in contact with the top interface of the low-temperature Dewar 301 (before inserting the sample rod 200, ensure that the sealing sleeve flange 217 is already located at the top interface of the low-temperature Dewar 301), at this time the resonant cavity 222 and the sample have entered the center of deep low temperature and strong magnetic field. At this time, the whole system is shown in Figure 5. The insertion process should be slow, because the temperature difference between inside and outside is huge, and slow insertion is beneficial to protect the system and samples, and also save low-temperature medium (liquid helium). During the whole process of inserting the sample rod 200 , it is necessary to ensure that high-purity helium gas with a pressure higher than atmospheric pressure is discharged from the top interface of the low-temperature Dewar 301 . Fasten the position of the sealing sleeve flange 217 with a tight buckle. Then the head-top box cover 202 is slightly opened, so that the air in the head-top box 201 is exhausted. Stop inputting high-purity helium gas to the low-temperature Dewar 301 and close the overhead box cover 202 to make it airtight. An external coaxial cable is connected to the outer end of the coaxial waveguide conversion head 208 to transmit the microwaves to the bottom of the sample holder 200 where the sample is located. Another external coaxial cable wire is connected to the outer end of the coaxial cable adapter 209 to receive and measure the microwave response. When performing contact measurements, connect the outer end of the test lead adapter A210 or test lead adapter B211 to the outer shielded cable. After the system is connected, the cryogenic liquid liquid helium is injected into the sample. At this time, the sample is at a low temperature of about 4.2K. The sample chamber of the cryogenic Dewar 301 is pumped and decompressed, and the temperature in the sample chamber can be reduced to 1.3K. about. After the system stabilizes to the required test temperature, the microwave measurement can be performed on the sample.

This patent has the following advantages: the waveguide and coaxial cable are introduced into the sample rod at the same time, and microwave signals in a wide range of power and frequency can be introduced to the sample in an extremely low temperature and strong magnetic field environment, realizing the solid material electrical In situ microwave measurements of properties. The body material of the waveguide is titanium metal with low thermal conductivity, which can ensure the stability of the sample temperature at extremely low temperature.

Description of drawings

FIG. 1 : a basic structure diagram of a sample rod 200 . The parts in the figure are: head-top box 201, head-top box cover 202, protective cover 203, fixed hinge 204, fixed hinge 205, frequency multiplier 206, rectangular-circle converter 207, coaxial waveguide conversion head 208, coaxial cable adapter 209. Test line adapter A210, test line adapter B211, coaxial waveguide connection line 212, coaxial cable 213, test lead A214, test lead B215, sealing O-ring 216, sealing sleeve flange 217, waveguide 218 , 4 lead tubes 219, 5 support discs 220, a bottom fixing frame 221, and a resonant cavity 222.

FIG. 2 : Schematic diagram of the three-dimensional structure of the fixed hinge 204 and the fixed hinge 205 .

FIG. 3 : a schematic plan view of the planar structure of five rack discs 220 .

FIG. 4 : Schematic diagram of the three-dimensional structure of the bottom fixing frame 221 .

FIG. 5 : Schematic diagram of the working principle of the sample rod 200 . The various parts in the figure are: the whole sample rod 200 , the main body of the low temperature Dewar 301 , the superconducting magnet 302 and the sample 303 .

Detailed ways

A better example of this patent is given below according to the content of the patent and the accompanying drawings, and the technical details, structural features and functional characteristics of this patent are further explained in conjunction with the examples. But this example does not limit the scope of this patent, and the examples described in the summary of the invention and the description of the drawings should be included in the scope of this patent.

All parts of the sample rod 200 are required to be non-magnetic, otherwise damage and interference will be caused under a strong magnetic field. The overhead box 201, the overhead box cover 202, the protective cover 203, the fixed hinge 204, the fixed hinge 205, the five support discs 220 and the bottom fixed frame 221 are all made of non-magnetic stainless steel, and the waveguide 218 and the four lead tubes 219 are all Titanium material. The diameter of the waveguide 218 is 10.0 mm, the diameter of the four lead tubes 219 is 5.6 mm, the diameter of the five support discs 220 is 3.5 cm, and the thickness is 1 mm. The bottom fixing frame 221 and the resonance cavity 222 have a diameter of 3.5 cm.

The head-top box 201 is a cylindrical hollow body with a bottom outer diameter of 16.6cm, an inner diameter of 16.0cm, and a height of 16.5cm. The top surface has a horizontally protruding outer edge, so the outer diameter is slightly larger at 18.0cm, and the inner diameter is still 16.0cm. ,. The internal volume of the head-top box 201 should ensure that the frequency multiplier 206 and the rectangular converter 207 can be accommodated. There are four outlets on the side wall of the head-top box 201, which are respectively used for installing the coaxial waveguide adapter 208, the coaxial cable adapter 209, the test line adapter A210 and the test line adapter B211. The coaxial waveguide adapter 208 and the coaxial cable adapter 209 need to be sealed with sealant to prevent air from entering the sample chamber, and the test line adapter A210 and the test line adapter B211 are self-sealing due to their sealing O-rings. The diameter of the head-top box cover 202 is the same as that of the bottom surface of the head-top box 201, and the thickness is about 10mm. The protective cover 203 connected to the bottom of the head-top box 201 has an outer diameter of about 3.0 cm, an inner diameter of 2.8 cm, and a height of 8.0 cm, and its bottom port matches the top port of the cryogenic Dewar 301 .

The coaxial waveguide conversion head 208 and the coaxial cable adapter 209 adopt a side-entry structure, applicable frequency 20-40GHz, relative bandwidth 41%, externally adapted to the coaxial cable of the microwave signal source, the interface is a bolt type, and the internal connection frequency multiplier The waveguide interface of the device 206 is nested. Both sides of the coaxial cable adapter 209 are connected with coaxial cables. The outer interface is bolted, which is the same as the coaxial waveguide adapter 208. The inner interface is nested, and the coaxial cable 213 is inserted therein, and the inner and outer conductive layers are respectively connected.

The test line adapter A210 is a 19-pin male socket, and the test line adapter B211 is a 21-pin male socket. The test lead A214 or test lead B215 respectively connected to them is a multi-core mutually insulated enamelled copper wire with a corresponding number of pins.

The lower part of the bottom fixing frame 221 is about 5 cm long, and 4 lead pipes 219 are extended from the lower ends. It is a parallel double-arm structure. The inner distance between the arms is 1.5 cm, the width of the arms is 2.5 cm, and the thickness is 3 mm. The holes are connected with the resonant cavity 222 by bolts. The resonant cavity 222 is independently designed and manufactured, and its upper part is a parallel double arm structure, which matches the parallel double arms of the bottom fixing frame 221 .

Claims (7)

1. A sample rod for non-contact low-temperature magnetic transport testing, which comprises an overhead box (201), an overhead box cover (202), a protective cover (203), a fixed hinge (204), a fixed hinge (205), a double frequency converter (206), rectangular converter (207), coaxial waveguide adapter (208), coaxial cable adapter (209), test line adapter A (210), test line adapter B (211), Coaxial waveguide connection wire (212), coaxial cable (213), test lead A (214), test lead B (215), sealing O-ring (216), sealing sleeve flange (217), waveguide ( 218), 4 lead tubes (219), 5 support discs (220), bottom fixing frame (221) and resonant cavity (222), characterized in that: The head-top box (201) is welded to the protective cover (203), the waveguide (218), and 4 lead pipes (219), and the waveguide (218) and the 4 lead pipes (219) pass through 5 support discs (220), The bottom fixing frame (221) is fixed together, the resonant cavity (222) is connected with the bottom fixing frame (221) by screws, and the waveguide (218) is fixed on the five support discs (220) and the bottom fixing frame (221). On the central round hole, 4 lead tubes (219) are fixed on the edge symmetrical round holes of 5 support discs (220) and the bottom fixing frame (221); the diameter of the top box cover (202) is the same as that of the top box (201) match, use the fixed hinge (204) and the fixed hinge (205) to seal with the head-top box (201) through the sealing O-ring (216); the coaxial cable (213), the test lead A (214) and the test lead B ( 215), one end of which enters the sample at the bottom of the sample rod through any one of the four lead tubes (219), and the other end is respectively connected with the coaxial cable adapter (209), test line adapter A (210), test Connect to the cable adapter B (211). 2. The sample rod of a non-contact low-temperature magnetic transport test according to claim 1, characterized in that: said head-top box (201), head-top box cover (202), protective cover (203), fixed Hinge (204), fixed hinge (205), sealing sleeve flange (217), 5 support discs (220), bottom fixed frame (221) all adopt non-magnetic stainless steel to make. 3. The sample rod of a non-contact low-temperature magnetic transport test according to claim 1, characterized in that: the waveguide (218) and the four lead tubes (219) adopt high hardness and low thermal conductivity Made of titanium. 4. The sample rod of a non-contact low-temperature magnetic transport test according to claim 1, characterized in that: the top box (201) is open at the top, and its bottom is sealed with the top of the protective cover (203) Welding, and seal welding with the waveguide (218) and the lead tube (219); there is a semicircular groove on the top section of the side wall to place the sealing O-ring (216), so as to seal with the head box cover (202) ; The two sides of the top of the side wall are respectively welded with horizontal support bars, which are respectively used to connect the fixed hinge (204) and the fixed hinge (205); four circular holes are opened on the side wall, which are respectively used to place the coaxial waveguide conversion head (208), coaxial cable conversion head (209), test line adapter A (210) and test line adapter B (211); its inner bottom surface is welded with the rectangular converter (207); The frequency multiplier (206) is connected to the rectangular converter (207), and the frequency multiplier (206) is connected to the waveguide (218) through the rectangular converter (207). 5. A sample rod for non-contact low-temperature magnetic transport testing according to claim 1, characterized in that: the five support disks (220) are provided with a central large circular hole and are symmetrically located near the edges There are four small round holes on the edge of which there are two side slots perpendicular to each other to meet the needs of pumping and decompression in the sample rod during decompression and cooling. 6. The sample rod of a kind of non-contact low-temperature magnetic transport test according to claim 1, characterized in that: the bottom fixing frame (221), its upper part is tightly plugged in the waveguide (218) and four Lead tube (219) lower end face, its bottom stretches out parallel double arm, connects and uses for resonant cavity (222). 7. A sample rod for non-contact low-temperature magnetic transport testing according to claim 1, characterized in that: the resonant cavity (222) is in the shape of a basket, the sample is placed in the bottom cavity, and its upper part extends Go out parallel double arm, match and connect with the parallel double arm of bottom fixed mount (221).

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