CN114152902A - SQUID probe based on thin film bridge Josephson junction and use method thereof - Google Patents

SQUID probe based on thin film bridge Josephson junction and use method thereof Download PDF

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CN114152902A
CN114152902A CN202111467286.0A CN202111467286A CN114152902A CN 114152902 A CN114152902 A CN 114152902A CN 202111467286 A CN202111467286 A CN 202111467286A CN 114152902 A CN114152902 A CN 114152902A
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squid
probe
thin film
silicon substrate
josephson junction
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CN114152902B (en
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潘银萍
张登辉
韩海龙
曾俊文
陈垒
王镇
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Shanghai Institute of Microsystem and Information Technology of CAS
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Shanghai Institute of Microsystem and Information Technology of CAS
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/035—Measuring direction or magnitude of magnetic fields or magnetic flux using superconductive devices
    • G01R33/0354—SQUIDS
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/035—Measuring direction or magnitude of magnetic fields or magnetic flux using superconductive devices
    • G01R33/0354—SQUIDS
    • G01R33/0356—SQUIDS with flux feedback

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  • General Physics & Mathematics (AREA)
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Abstract

The invention provides a SQUID probe based on a thin film bridge Josephson junction and a use method thereof, wherein the structure comprises the following components: a silicon substrate, wherein one end of the silicon substrate is formed into a needle point shape by a deep silicon etching technology; a device probe end including a first SQUID formed on a tip-shaped end of the silicon substrate; a device cancellation end comprising a second SQUID formed at the end remote from the device probe; a first feedback coil and a second feedback coil. The SQUID probe is combined with a deep silicon etching technology to arrange a device probe end prepared on a silicon substrate on the end of the tip shape of the silicon substrate, so that the distance between a first SQUID and the edge of the tip end of the silicon substrate can be accurately controlled, the magnetic coupling strength between the SQUID and the surface of a sample is improved, and the SQUID probe structure and a tuning fork can be combined in a resonant mode to realize accurate tip-sample distance control when the SQUID probe is used, so that the spatial resolution of the SQUID probe on the silicon substrate is greatly improved; in addition, the multifunctional measurement of the probe can be realized by combining the first feedback coil and the second feedback coil which are integrated on the silicon substrate.

Description

SQUID probe based on thin film bridge Josephson junction and use method thereof
Technical Field
The invention relates to the field of superconducting quantum interference devices (SQUIDs), in particular to a SQUID probe based on a thin film bridge Josephson junction and a using method thereof.
Background
With the development of spintronics and superconducting electronics, the study of direct magnetic response of materials at the microscopic scale can reveal many other undetectable properties, such as observation of nanoparticle magnetization relaxation processes, magnetic flux imaging in nanowires, and magnetic flux quantization and vortex detection of superconductors. A direct current squid (superconducting quantum interference devices) formed by connecting two Josephson Junctions (JJ) in parallel is one of the most sensitive known magnetic flux sensors, and the detection sensitivity of the direct current squid (superconducting quantum interference devices) can approach the quantum limit. In microscopic magnetic imaging, the SQUID probe is matched with SSM (scanning SQUID Microcopy) consisting of a high-precision three-axis scanning platform, and by virtue of high magnetic field sensitivity and weak magnetic coupling nondestructive reading, submicron magnetic flux imaging can be realized, and diversified tests such as current density distribution, magnetic flux imaging, magnetic susceptibility measurement and the like can be simultaneously carried out on an integrated coil on a silicon chip, so that the superconducting magnetic imaging system is a powerful tool for analyzing the microstructure of material components and substances.
Compared with the traditional SQUID, the nano-SQUIDs have smaller size, so that the nano-SQUIDs have more advantages in the aspect of magnetic moment measurement. Spin sensitivity S of SQUID under ideal coupling conditionsnThe following formula is satisfied: sn＝2aφn/μBμ0Where a is the SQUID loop size, indicating that the magnetic moment detectable by the SQUID is directly proportional to the SQUID loop size. The typical loop size of a nano-SQUID is from tens of nanometers to hundreds of nanometers, which has lower magnetic flux noise compared to a conventional SQUID, and thus the nano-SQUID has higher spin sensitivity. The SQUID formed by the thin film bridge Josephson junction can most easily realize a nanometer level SQUID loop, for example, nano-SQUID (SOT) prepared on a quartz glass tube needle point can realize the magnetic imaging resolution of about 50 nm. Unfortunately, this approach does not integrate a feedback coil or excitation coil, SQUID flux-locked sensing, and more functional magnetic property measurement. However, nano-The SQUID can integrate an on-chip feedback coil, thereby adopting a magnetic flux locking readout method, and can integrate an excitation coil to realize multifunctional measurement of current density distribution and magnetic susceptibility.
The SQUID probe prepared on the silicon chip at present has the following defects: firstly, the SQUID loop has larger area for realizing a gradiometer structure and offsetting the action of an external field; secondly, the SQUID probe is far away from the edge of the silicon chip, so that the distance between a SQUID capture magnetic flux loop and a sample is limited during scanning application, and accurate distance control cannot be achieved, so that the spatial resolution of a scanning SQUID microscope is limited; in addition, most of conventional SQUID probes are prepared on the basis of superconducting thin films Nb, and the maximum working temperature of the SQUID probes is about 6K, so that the SQUID probes have higher requirements on the temperature of a sample and are not beneficial to discovery of more physical novelty phenomena.
Disclosure of Invention
In view of the above-described shortcomings of the prior art, it is an object of the present invention to provide a thin film bridge josephson junction-based SQUID probe and a method of using the same for solving at least one of the above problems of the SQUID probe fabricated on a silicon wafer in the prior art.
To achieve the above and other related objects, the present invention provides a SQUID probe based on a thin film bridge josephson junction, the SQUID probe structure comprising:
the silicon substrate is characterized by comprising a silicon substrate, wherein one end of the silicon substrate is formed into a needle point shape through a deep silicon etching technology;
a device probe end including a first SQUID formed on a tip-shaped end of the silicon substrate, the first SQUID being composed of a thin film bridge josephson junction;
a device cancellation end comprising a second SQUID formed on said silicon substrate and distal to said device probe end, said second SQUID being identical to said first SQUID;
and the first feedback coil and the second feedback coil are respectively and correspondingly coupled with the first SQUID and the second SQUID so as to realize the SQUID loop magnetic flux locking and reading functions corresponding to the first feedback coil and the second feedback coil.
Optionally, the first SQUID and the second SQUID operate simultaneously, so that simultaneous measurement of the two-channel SQUIDs is realized.
Optionally, the first SQUID and the second SQUID are 3D nano-SQUIDs; the 3D nano-SQUID comprises a superposed structure of a superconducting thin film layer, an insulating layer and a superconducting thin film layer which are sequentially superposed along the transverse direction of a device and two 3D superconducting nano-bridges arranged on the superposed structure, wherein the insulating layer is also formed below the superconducting thin film layer in the superposed structure, the two 3D superconducting nano-bridges are arranged at intervals and cross the superposed structure, and the insulating layer between the two 3D superconducting nano-bridges forms a SQUID loop.
Further, the SQUID loop has a width of 20 nm-50 nm and a length of 50 nm-800 nm.
Optionally, the first SQUID and the second SQUID are 3D nano-SQUIDs; 3D nano-SQUID include along the device transverse direction superconductive thin layer-insulating layer-superconductive thin layer's of superpose in proper order superpose superposed structure and set up in two 3D superconductive nanometer bridges on the superposed structure, just one in the superposed structure superconductive thin layer below also is formed with the insulating layer, wherein, two 3D superconductive nanometer bridge interval sets up and spanes superposed structure, the lower floor has the insulating layer place be formed with the sculpture window on the superconductive thin layer, this sculpture window exposes the lower floor the insulating layer reaches in the superposed structure the partial lateral wall of insulating layer, two between the 3D superconductive nanometer bridge insulating layer and naked lower floor the insulating layer constitutes the SQUID loop.
Furthermore, the superconducting thin film layer and the 3D superconducting nano bridge are made of niobium nitride, and the insulating layer is made of silicon dioxide or magnesium oxide.
The invention also provides a use method of the SQUID probe based on the thin film bridge Josephson junction, which comprises the following steps: when the SQUID probe works, the SQUID probe is adhered to one pin of a tuning fork, the other pin of the tuning fork is adhered to a vibrating piezoelectric ceramic, the tuning fork is connected with a phase-locked amplifier, the phase-locked amplifier monitors the resonant peak and the phase change of the tuning fork in real time, and the extension and the contraction of the voltage regulation displacer are controlled through a PID feedback loop according to the monitoring result of the phase-locked amplifier.
Optionally, the method of use achieves a sample step size control range of 5 nm.
Optionally, when the SQUID probe is used, the SQUID probe, the tuning fork, the scanner and the displacer are placed in a vacuum sandwich in the middle of a layer of liquid helium.
Further, the use method realizes sample measurement within the temperature difference range of 1.5K-240K, wherein the temperature difference is the temperature difference between the SQUID probe structure and the sample.
As described above, the SQUID probe based on the thin film bridge Josephson junction and the use method thereof, the SQUID probe structure combines the deep silicon etching technology to arrange the probe end of a device prepared on the silicon substrate on the end of the tip shape of the silicon substrate, the distance between the first SQUID and the edge of the tip of the silicon wafer can be accurately controlled, so that the magnetic coupling strength between the SQUID and the surface of a sample is improved, and the SQUID probe structure and tuning fork resonance can be combined to realize accurate tip-sample distance control when in use, so that the spatial resolution of the SQUID probe on the silicon substrate is greatly improved; in addition, the multifunctional measurement of the probe can be realized by combining the first feedback coil and the second feedback coil which are integrated on the silicon substrate.
Drawings
Figure 1 shows a schematic diagram of a thin film bridge josephson junction-based SQUID probe of the present invention.
Figure 2 shows a scanning schematic of a thin film bridge josephson junction based SQUID probe of the present invention.
Fig. 3 shows a schematic three-dimensional structure of the first SQUID or the second SQUID in the thin film bridge josephson junction-based SQUID probe according to an embodiment of the present invention.
Fig. 4 shows a schematic perspective view of the first SQUID or the second SQUID in the thin film josephson junction-based SQUID probe according to another embodiment of the present invention.
Fig. 5 is a top view of fig. 4.
Fig. 6 shows a schematic diagram of the combination of the thin film josephson junction-based SQUID probe of the present invention and tuning fork for achieving precise height control, and the lower right diagram of fig. 6 shows a graph of the displacement between the sample and the SQUID probe structure and the vibration amplitude and phase of the tuning fork.
Figure 7 shows the temperature of the thin film bridge josephson junction based SQUID probe of the present invention plotted against the measurable maximum sample temperature, with the temperature of the SQUID probe structure on the abscissa and the temperature of the sample on the ordinate.
Description of the element reference numerals
10 silicon substrate
101 tip shape
11 device probe end
12 device cancellation end
13 first feedback coil
14 second feedback coil
15 first SQUID
16 second SQUID
171 superconductive thin film layer
172 insulating layer
1733D superconducting nanobridge
174 SQUID loop
175 etch window
18 tuning fork
19 piezoelectric ceramics
20 phase-locked amplifier
21 PID feedback loop
22 shifter
23 sample holder
24 samples
25 liquid helium layer
26 vacuum interlayer
27 scanning head
28 SQUID Probe
29 circuit lead-out wire
30 metal heat conducting layer
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Please refer to fig. 1 to 6. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of each component in actual implementation may be changed according to actual needs, and the layout of the components may be more complicated.
As shown in fig. 1 to 4, the present embodiment provides a SQUID probe based on a thin film bridge josephson junction, the SQUID probe comprising:
a silicon substrate 10, wherein one end of the silicon substrate 10 is formed into a needle point shape 101 through a deep silicon etching technology;
a device probe end 11 including a first SQUID15 formed on the tip end of the silicon substrate 10 at the tip shape 101, the first SQUID15 being comprised of a thin film bridge josephson junction;
a device cancellation end 12 comprising a second SQUID16 formed on said silicon substrate 10 distal to said device probe end 11, said second SQUID16 being identical to said first SQUID 15;
the first feedback coil 13 and the second feedback coil 14 are respectively and correspondingly coupled with the first SQUID15 and the second SQUID16, so as to realize the SQUID loop magnetic flux locking and reading functions respectively corresponding to the two coils.
The SQUID probe provided by the embodiment is combined with a deep silicon etching technology, the probe end of a device prepared on a silicon substrate is arranged on the end of the silicon substrate where the tip shape is located, the distance between the first SQUID and the edge of the tip end of the silicon wafer can be accurately controlled, the magnetic coupling strength between the SQUID and the surface of a sample is improved, and the SQUID probe and a tuning fork can be combined in a resonant mode to realize accurate tip-sample distance control when the SQUID probe is used, so that the spatial resolution of the SQUID probe on the silicon substrate is greatly improved; in addition, the multifunctional measurement of the probe structure can be realized by combining the first feedback coil and the second feedback coil which are integrated on the silicon substrate.
As shown in fig. 1 and 2, for example, the first SQUID15 and the second SQUID16 operate simultaneously, and the two-channel SQUID simultaneous measurement is realized. The first SQUID15 measures an external uniform magnetic field and a sample magnetic field, the second SQUID16 measures an external uniform magnetic field, the uniform external magnetic field can be offset by simultaneous measurement of the two SQUIDs, background magnetic noise is eliminated, the signal-to-noise ratio of the whole system is improved, and the magnetic flux imaging function of offsetting the external uniform magnetic field is realized.
As shown in fig. 3, by way of example, the first SQUID15 and the second SQUID16 are 3D nano-SQUIDs; the 3D nano-SQUID comprises a superposed structure of a superconducting thin film layer 171-an insulating layer 172-a superconducting thin film layer 171 sequentially superposed along the transverse direction of the device and two 3D superconducting nano-bridges 173 arranged on the superposed structure, wherein the insulating layer 172 is also formed below the superconducting thin film layer in one of the superposed structures, the two 3D superconducting nano-bridges 173 are arranged at intervals and cross the superposed structure, and the insulating layer 172 between the two 3D superconducting nano-bridges 173 forms a SQUID loop 174. The structure can reduce the loop area of the SQUID loops 174 of the first SQUID and the second SQUID to a nanometer level, and improve the spin sensitivity and the spatial resolution. As a specific example, the method for preparing the 3D nano-SQUID is as follows: firstly, forming the superconducting thin film layer 171 on the left side on the silicon substrate 10; then, depositing the insulating layer 172 on the sidewall of the left superconducting thin film layer 171 and the surface of the silicon substrate 10 by using a deposition process, and depositing the insulating layer 172 with a certain thickness to form the right superconducting thin film layer 171 in a groove formed by the insulating layer 172, thereby obtaining the stacked structure, wherein the insulating layer 172 is deposited by using the deposition process, the method can effectively control the thickness of the insulating layer 172, that is, the area of the SQUID loop 174 can be subsequently effectively controlled, in this embodiment, the width of the SQUID loop 174 can be between 20nm and 50nm, and the length of the SQUID loop 174 can be between 50nm and 800 nm; two of the 3D superconducting nanobridges 173 are then formed on the stacked structure using electron beam lithography.
As another example, as shown in fig. 4 and 5, the first SQUID15 and the second SQUID16 are 3 Dnano-SQUIDs; the 3D nano-SQUID comprises an overlapping structure of a superconducting thin film layer 171-an insulating layer 172-a superconducting thin film layer 171 sequentially overlapped along the transverse direction of the device and two 3D superconducting nano-bridges 173 arranged on the overlapping structure, wherein the insulating layer 172 is also formed below the superconducting thin film layer 171 in the overlapping structure, the two 3D superconducting nano-bridges 173 are arranged at intervals and cross the overlapping structure, an etching window 175 is formed on the superconducting thin film layer 171 where the insulating layer 172 is located at the lower layer, the etching window 175 exposes the lower layer of the insulating layer 172 and part of the side wall of the insulating layer 172 in the overlapping structure, and the insulating layer 172 and the exposed lower layer between the two 3D superconducting nano-bridges 173 form a SQUID loop 174 (as shown in fig. 5). The structure can enlarge the loop area of the SQUID loop 174 of the first SQUID and the second SQUID to the micron level, and meets the requirement of higher magnetic field sensitivity. In a specific application, the SQUID loop 174 shown in fig. 3 or the SQUID loop 174 shown in fig. 4 may be selected according to actual needs. As a specific example, the method for preparing the 3D nano-SQUID is as follows: firstly, forming the superconducting thin film layer 171 on the left side on the silicon substrate 10; then, depositing the insulating layer 172 on the sidewall of the superconducting thin film layer 171 on the left and the surface of the silicon substrate 10 by using a deposition process, and forming the superconducting thin film layer 171 on the right in a groove formed by the insulating layer 172 after depositing the insulating layer 172 with a certain thickness, thereby obtaining the stacked structure; then, two 3D superconducting nano-bridges 173 are formed on the stacked structure by using an electron beam lithography technique; finally, the superconducting thin film layer 171 formed in the groove is etched to form an etching window 175, so that the etching window 175 exposes the lower insulating layer 172 and a part of the sidewall of the insulating layer 172 in the stacked structure.
Based on the 3D nano-SQUID structures shown in fig. 3 and 4, the material of the superconducting thin film layer 171 and the 3D superconducting nano-bridge 173 is niobium nitride, and the material of the insulating layer 172 is conventionally selected from materials with good insulating property, such as silicon dioxide or magnesium oxide, and good sidewall wrapping property. The 3D nano-SQUID structure prepared by selecting niobium nitride material has higher superconducting transition temperature and critical magnetic field, and the maximum working temperature can reach about 10K.
Based on the SQUID probe based on the thin film josephson junction, the present embodiment also provides a method for using the SQUID probe, as shown in fig. 6, the method comprises: when the SQUID probe works, the SQUID probe 28 is pasted on one pin of the tuning fork 18, the other pin of the tuning fork 18 is pasted on one shaking piezoelectric ceramic 19, the tuning fork 18 is connected with the phase-locked amplifier 20, the phase-locked amplifier 20 monitors the formant and the phase change of the tuning fork 18 in real time, and controls the extension and the contraction of the voltage regulation displacer 22 through the PID feedback loop 21 according to the monitoring result of the phase-locked amplifier 20. The method specifically comprises the following steps: control of the separation of the sample 24 and SQUID probe 28 is based on the sensitivity of the tuning fork 18 to vibration, affixing the SQUID probe 28 to one pin of the tuning fork 18, the other pin of the tuning fork 18 is stuck on a shaking piezoelectric ceramic 19, and the piezoelectric ceramic 19 is driven by alternating current with certain frequency to vibrate the tuning fork 18 up and down mechanically, when the frequency of the alternating current coincides with the natural frequency of the tuning fork 18, the two resonate, the voltage signal between the two pins of the tuning fork 18 is demodulated into vibration amplitude and phase values via the lock-in amplifier 20, when the sample 24 surface contacts the edge of the deep silicon etched SQUID probe 28, i.e., the probe end of the device, the vibration amplitude of the tuning fork 18 is sharply decreased, and the phase value is sharply increased, and such a sharp change can be controlled within a step size range of 5nm, which can be observed by the formant and phase change of the tuning fork 18. Therefore, as the sample 24 is advanced by the displacer 22 to approach the device probe end of the SQUID probe 28, the amplitude of the tuning fork 18 vibration is monitored in real time and the extension or contraction of the displacer 22 (i.e., the Scanner Z) is controlled by feedback. In the precession process, a feedback working point is set to be smaller than the vibration amplitude of the tuning fork 18 when the tuning fork 18 is contacted with the SQUID probe 28, then the extension shifter 22 is driven by voltage until the monitored vibration amplitude of the tuning fork 18 reaches the set working point, and finally the extension and contraction of the output voltage regulation shifter 22 are controlled through a feedback loop, so that the distance between the sample 24 and the device detection end of the SQUID probe 28 is kept unchanged in the scanning process, the distance can be controlled at several nanometer levels, accurate height control is realized, and the device probe end prepared on the silicon substrate is arranged on the end of the tip shape of the silicon substrate by combining a deep silicon etching technology, so that the spatial resolution of the SQUID probe is greatly improved.
As shown in fig. 6, to achieve a large temperature difference between sample 24 and SQUID probe 28, as an example, a test system comprising SQUID probe 28, tuning fork 18, scanning head 27 and displacer 22 is placed in vacuum sandwich 26 between liquid helium layer 25, reducing the thermal conductivity between sample 24 and SQUID probe 28 by the principle of vacuum thermal conductivity difference. The SQUID probe 28 is thermally connected with the liquid helium layer 25 through a metal block with good thermal conductivity, the temperature is controlled to be below 10K of the working temperature of the niobium nitride film, a heating wire is adhered in the sample holder 23, the sample is heated by electrifying current to the heating wire, the maximum temperature difference of 240K between the SQUID probe 28 and the sample 24 can be realized, namely the SQUID probe 28 is at the temperature of about 10K, the sample 24 is at 250K, as shown in figure 7, the maximum working temperature of the SQUID probe of the niobium nitride material can reach 10K, and the sample 24 can be measured within the temperature difference range of 1.5K-240K by combining the vacuum heat insulation technology, wherein the temperature difference is the temperature difference between the SQUID probe 28 and the sample 24; the wet test system does not need to use a compressor required by a conventional dry refrigerator to work, so that vibration can be effectively reduced, and the test precision is improved.
In conclusion, the SQUID probe based on the thin film bridge Josephson junction and the use method thereof are provided, the SQUID probe is combined with a deep silicon etching technology to arrange a probe end of a device prepared on a silicon substrate on the end of the tip shape of the silicon substrate, the distance between a first SQUID and the edge of the tip of the silicon wafer can be accurately controlled, so that the magnetic coupling strength between the SQUID and the surface of a sample is improved, and the SQUID probe and a tuning fork can be combined in resonance to realize accurate tip-sample distance control during use, so that the spatial resolution of the SQUID probe on the silicon substrate is greatly improved; in addition, the multifunctional measurement of the probe structure can be realized by combining the first feedback coil and the second feedback coil which are integrated on the silicon substrate. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims (10)

1. A thin film bridge josephson junction-based SQUID probe, the SQUID probe structure comprising:
the silicon substrate is characterized by comprising a silicon substrate, wherein one end of the silicon substrate is formed into a needle point shape through a deep silicon etching technology;
a device probe end including a first SQUID formed on a tip-shaped end of the silicon substrate, the first SQUID being composed of a thin film bridge josephson junction;
a device cancellation end comprising a second SQUID formed on said silicon substrate and distal to said device probe end, said second SQUID being identical to said first SQUID;
and the first feedback coil and the second feedback coil are respectively and correspondingly coupled with the first SQUID and the second SQUID so as to realize the SQUID loop magnetic flux locking and reading functions corresponding to the first feedback coil and the second feedback coil.
2. The thin film josephson junction-based SQUID probe of claim 1, wherein: and the first SQUID and the second SQUID work simultaneously, so that the two-channel SQUID simultaneous measurement is realized.
3. The thin film josephson junction-based SQUID probe of claim 1, wherein: the first SQUID and the second SQUID are 3D nano-SQUIDs; the 3D nano-SQUID comprises a superposed structure of a superconducting thin film layer, an insulating layer and a superconducting thin film layer which are sequentially superposed along the transverse direction of a device and two 3D superconducting nano-bridges arranged on the superposed structure, wherein the insulating layer is also formed below the superconducting thin film layer in the superposed structure, the two 3D superconducting nano-bridges are arranged at intervals and cross the superposed structure, and the insulating layer between the two 3D superconducting nano-bridges forms a SQUID loop.
4. The thin film josephson junction-based SQUID probe of claim 3, wherein: the SQUID loop has a width of 20-50 nm and a length of 50-800 nm.
5. The thin film josephson junction-based SQUID probe of claim 1, wherein: the first SQUID and the second SQUID are 3D nano-SQUIDs; 3D nano-SQUID include along the device transverse direction superconductive thin layer-insulating layer-superconductive thin layer's of superpose in proper order superpose superposed structure and set up in two 3D superconductive nanometer bridges on the superposed structure, just one in the superposed structure superconductive thin layer below also is formed with the insulating layer, wherein, two 3D superconductive nanometer bridge interval sets up and spanes superposed structure, the lower floor has the insulating layer place be formed with the sculpture window on the superconductive thin layer, this sculpture window exposes the lower floor the insulating layer reaches in the superposed structure the partial lateral wall of insulating layer, two between the 3D superconductive nanometer bridge insulating layer and naked lower floor the insulating layer constitutes the SQUID loop.
6. The thin film josephson junction-based SQUID probe of any of claims 3 to 5, wherein: the superconducting thin film layer and the 3D superconducting nano bridge are made of niobium nitride, and the insulating layer is made of silicon dioxide or magnesium oxide.
7. A method of using the thin film Josephson junction based SQUID probe of any one of claims 1 to 6, comprising: when the SQUID probe works, the SQUID probe is adhered to one pin of a tuning fork, the other pin of the tuning fork is adhered to a vibrating piezoelectric ceramic, the tuning fork is connected with a phase-locked amplifier, the phase-locked amplifier monitors the resonant peak and the phase change of the tuning fork in real time, and the extension and the contraction of the voltage regulation displacer are controlled through a PID feedback loop according to the monitoring result of the phase-locked amplifier.
8. The method of using a thin film josephson junction based SQUID probe of claim 7, wherein: the use method realizes the control range of the sample step length of 5 nm.
9. The method of using a thin film josephson junction based SQUID probe of claim 7, wherein: when the SQUID probe is used, the SQUID probe, the tuning fork, the scanning head and the shifter are placed in a vacuum interlayer in the middle of a liquid helium layer.
10. The method of using a thin film josephson junction based SQUID probe of claim 9, wherein: the use method realizes sample measurement within the temperature difference range of 1.5K-240K, and the temperature difference is the temperature difference between the SQUID probe structure and the sample.
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