阅读说明：本技术 一种基于超导和隧穿磁电阻的高精度复合磁梯度计 (High-precision composite magnetic gradiometer based on superconductivity and tunneling magnetoresistance ) 是由 李裴森 胡佳飞 潘孟春 杨澜 张琦 彭俊平 邱伟成 冀敏慧 于 2020-05-26 设计创作，主要内容包括：本发明公开了一种基于超导和隧穿磁电阻的高精度复合磁梯度计,自下而上依次包括超导闭合环路层,绝缘层和隧穿磁电阻器件层,所述超导闭合环路层包括两个位于同一平面内且呈镜面对称设置的超导环,所述超导环包括窄区、宽区和用于连接窄区和宽区的连接部,两超导环的窄区靠近设置,所述隧穿磁电阻器件层位于两超导环窄区的上方,本发明具有结构简单,能对磁场梯度进行超高灵敏测试的优点。(The invention discloses a high-precision composite magnetic gradiometer based on superconductivity and tunneling magnetoresistance, which sequentially comprises a superconductivity closed loop layer, an insulating layer and a tunneling magnetoresistance device layer from bottom to top, wherein the superconductivity closed loop layer comprises two superconductivity rings which are positioned in the same plane and are arranged in mirror symmetry, each superconductivity ring comprises a narrow region, a wide region and a connecting part for connecting the narrow region and the wide region, the narrow regions of the two superconductivity rings are arranged close to each other, and the tunneling magnetoresistance device layer is positioned above the narrow regions of the two superconductivity rings.)

1. A high-precision composite magnetic gradiometer based on superconductivity and tunneling magnetoresistance is characterized in that: include superconductive closed loop layer (1), insulating layer (2) and tunneling magneto-resistance device layer (3) from bottom to top in proper order, superconductive closed loop layer (1) includes that two are located the coplanar and are superconducting ring (11) that mirror symmetry set up, superconducting ring (11) include narrow region (111), wide region (112) and are used for connecting portion (113) of narrow region (111) and wide region (112), and narrow region (111) of two superconducting ring (11) are close to the setting, tunneling magneto-resistance device layer (3) are located the top of two superconducting ring (11) narrow region (111).

2. The high accuracy composite magnetic gradiometer of claim 1, wherein: the distance between the narrow regions (111) of the two superconducting rings (11) is D, and D is more than 0 and less than or equal to 5 mu m.

3. The high accuracy composite magnetic gradiometer of claim 2, wherein: the magnetic field gradient is dH/dx, dH/dx = A (H)₁-H₂) X, A is the regional magnification of the tunneling magneto-resistance device layer (3), H₁For vertical penetration of a magnetic field in one of the superconducting rings (11), H₂Is a vertical penetration magnetic field in another superconducting ring (11), and x is the distance between the points to be detected in the two wide regions (112).

4. The high accuracy composite magnetic gradiometer of claim 3, wherein: the point to be detected in the two wide areas (112) is the central point of the two wide areas (112).

5. The high accuracy composite magnetic gradiometer of any of claims 1 to 4, wherein: the superconducting ring (11) is prepared from an yttrium barium copper oxide high-temperature superconducting material.

6. The high accuracy composite magnetic gradiometer of claim 5, wherein: the thickness s1 of the superconducting ring (11) is 200-600 nm.

7. The high accuracy composite magnetic gradiometer of claim 5, wherein: the wide region (112) of the superconducting ring (11) has a line width of d1, an outer diameter of d2, and d1/d2= 0.2-0.3.

8. The high accuracy composite magnetic gradiometer of any of claims 1 to 4, wherein: the tunneling magneto-resistance device layer (3) is prepared by adopting an MgO-based magnetic tunnel junction.

9. The high accuracy composite magnetic gradiometer of any of claims 1 to 4, wherein: the insulating layer (2) is prepared from silicon dioxide.

10. The high accuracy composite magnetic gradiometer of claim 9, wherein: the thickness s2 of the insulating layer (2) is 100nm-300 nm.

Technical Field

The invention relates to the field of magnetic sensors, in particular to a high-precision composite magnetic gradiometer based on superconductivity and tunneling magnetoresistance.

Background

The weak magnetic detection has important function and wide application prospect in the fields of scientific research, national defense and military industry, industrial production and the like. Due to the existence of background signals such as the earth magnetic field, weak magnetic detection has great challenges. The traditional magnetic shielding technology can inhibit background signals to a certain extent, but has high manufacturing cost, difficult processing and large volume. The magnetic gradiometer can obtain effective weak magnetic signals without magnetic shielding, and an important way is provided for developing research and application of the weak magnetic signals. For example, for measuring biomagnetic signals, the magnetic gradiometer can be placed closer to the patient, improving the accuracy of the measurement.

At present, the detection of weak signal gradient is mainly based on a planar magnetic field gradiometer consisting of a superconducting quantum interference device and a magnetic field gradient coil, wherein two identical coils are required to be prepared and symmetrically placed in a superconducting loop, and the problem of inductance matching between the superconducting quantum interference device and the magnetic field gradient coil is also required to be considered, so that the preparation difficulty of the device is high, and the process is complex; in addition, the superconducting quantum interference device is a superconducting ring, and when the gradient of an external magnetic field is zero, the device has non-zero response and cannot output an ideal gradient signal; and the whole system of the device has the defects of large volume and low integration level.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a high-precision composite magnetic gradiometer based on superconductivity and tunneling magnetoresistance, which is simple in structure and can be used for carrying out ultra-high sensitive test on magnetic field gradients.

In order to solve the technical problems, the invention adopts the following technical scheme:

the utility model provides a compound magnetic gradiometer of high accuracy based on superconduction and tunneling magnetoresistance, includes superconductive closed loop layer, insulating layer and tunneling magnetoresistance device layer from bottom to top in proper order, superconductive closed loop layer includes that two are located the coplanar and are the superconducting ring that mirror symmetry set up, the superconducting ring includes narrow district, wide district and is used for connecting the connecting portion in narrow district and wide district, and the narrow district of two superconducting rings is close to the setting, tunneling magnetoresistance device layer is located the top in two superconducting ring narrow districts.

As a further improvement of the above technical solution:

the distance between the two superconducting loop narrow regions is D, and D is more than 0 and less than or equal to 5 mu m.

The magnetic field gradient is dH/dx, dH/dx = A (H)₁-H₂) X, A is the regional magnification of the tunneling magneto-resistance device layer, H₁For vertical penetration of a magnetic field in one of the superconducting rings, H₂Is a vertical penetrating magnetic field in another superconducting ring, and x is the distance between points to be detected in two wide regions.

The point to be detected in the two wide areas is the central point of the two wide areas.

The superconducting ring is prepared from a Yttrium Barium Copper Oxide (YBCO) high-temperature superconducting material.

The thickness s1 of the superconducting ring is 200-600 nm.

The line width of the wide region of the superconducting ring is d1, the outer diameter is d2, and d1/d2= 0.2-0.3.

The tunneling magneto-resistance device layer is prepared by adopting an MgO-based magnetic tunnel junction.

The insulating layer is prepared from silicon dioxide.

The thickness s2 of the insulating layer is 100nm-300 nm.

The working principle of the invention is as follows:

the invention adopts two superconducting rings with mirror symmetry as a superconducting magnetic flux converter to carry out difference and amplification on a magnetic field, and simultaneously utilizes a tunneling magneto-resistance device layer to carry out high-sensitivity test on the magnetic field gradient. Due to the superconductor meissner effect of the superconducting loop, below the superconducting transition temperature, when an external magnetic field vertically passes through the superconducting loop, shielding current is generated in the superconducting loop to offset the magnitude of the external magnetic field, and the current flowing through the superconductor is not uniformly distributed in the material, but rapidly attenuates inwards along the normal direction along with the width. The superconducting ring comprises a narrow region, a wide region and a connecting part for connecting the narrow region and the wide region, wherein the narrow region of the superconducting ring is limited by the width of the superconducting ring, so that the current density is rapidly increased, and the current distribution is changed along with the width, so that certain amplified magnetic field intensity is obtained in the narrow region.

Compared with the prior art, the invention has the advantages that:

the invention relates to a high-precision composite magnetic gradiometer based on superconductivity and tunneling magnetoresistance, wherein a superconducting ring is a closed loop comprising a narrow region (a section of narrow region) and a wide region, when a magnetic field vertically passes through the superconducting ring, shielding current is generated in the superconducting ring, when the shielding current passes through the narrow region, the current density in the narrow region is increased, and the magnetic field intensity around the narrow region is increased, so that the magnetic field aggregation and amplification are realized, and the ultrahigh sensitivity test is carried out on the magnetic field gradient. Compared with a superconducting quantum interference plane magnetic gradiometer, the superconducting quantum interference plane magnetic gradiometer has the advantages of simpler structure and preparation, small volume, low cost, stable performance, small process integration difficulty and no non-zero response, and can realize ultrahigh-precision detection of a weak magnetic field in a non-magnetic shielding environment.

Drawings

FIG. 1 is a top view of a high-precision composite magnetic gradiometer based on superconducting and tunneling magnetoresistance of the present invention.

FIG. 2 is a side view of a high precision composite magnetic gradiometer based on superconducting and tunneling magnetoresistance of the present invention.

Fig. 3 is a partially enlarged view of a portion a in fig. 2.

Fig. 4 is a graph of the magnetic field amplification factor over the insulating layer as a function of the horizontal distance from the narrow region, calculated for a single superconducting ring simulation of the current parameters.

The reference numerals in the figures denote: 1. a superconducting closed loop layer; 11. a superconducting ring; 111. a narrow region; 112. a wide region; 113. a connecting portion; 2. an insulating layer; 3. tunneling through the magnetoresistive device layer.

Detailed Description

The invention will be described in further detail below with reference to the drawings and specific examples. Unless otherwise specified, the instruments or materials employed in the present invention are commercially available.