Tunnel magnetoresistance magnetic detector with out-of-plane magnetic field detection capability

Abstract

The invention provides a tunnel magnetoresistance magnetic detector with out-of-plane magnetic field detection capability, which comprises a superconducting shielding layer which is of a rectangular superconducting thin film structure, and the direction of an external magnetic field perpendicular to the superconducting shielding layer is changed into the direction parallel to the superconducting shielding layer by utilizing the complete diamagnetism of a superconductor; the two tunnel magnetoresistors are located in edge areas on the two sides below the superconducting shielding layer respectively, the size of each tunnel magnetoresistor is smaller than that of the superconducting shielding layer, and the two tunnel magnetoresistors are the same in magnetic sensitive direction, parallel to the thin film plane of the superconducting shielding layer and used for detecting the magnetic field intensity parallel to the superconducting layer direction; the differential amplifier is used for amplifying differential signals of the two tunnel magnetoresistors; and the signal acquisition system is used for acquiring and processing the amplified differential signals of the two tunnel magnetoresistors. The problem that an existing tunnel magnetoresistor is difficult to detect a magnetic field in the out-of-plane direction is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of weak magnetic detection, and in particular relates to a tunnel magnetoresistance magnetic detector with out-of-plane magnetic field detection capability. Background Art

[0002] With the advantages of low power consumption, small size, and high magnetic field detection capability, magnetoresistive sensors have shown great application potential in the fields of biomedicine, geomagnetic navigation, and non-destructive testing. Among all types of magnetoresistive technologies, TMR (tunnel magnetoresistance) sensors show higher sensitivity, lower power consumption, and wider linear range compared to AMR (anisotropic magnetoresistance) and GMR (giant magnetoresistance) sensors, and are therefore widely considered to be an ideal magnetic sensor construction solution.

[0003] At present, most TMR magnetic sensors can only sense the magnetic field in the horizontal direction of the plane because their tunnel junction has in-plane magnetic anisotropy (IMA). In 2010, Ikeda et al. discovered significant interface perpendicular magnetic anisotropy in Ta / CoFeB / MgO heterostructures and successfully prepared a perpendicular magnetic tunnel junction, which enabled TMR devices to detect vertical magnetic fields. With the continuous deepening of research, the key performance of the perpendicular magnetic tunnel junction, including perpendicular magnetic anisotropy, thermal stability and TMR value, has been significantly improved. However, the current research on perpendicular magnetic tunnel junctions is still mainly focused on spin-torque transfer magnetic random access memory (Spin-Torque-Transfer Magnetic Random Access Memory, STT-MRAM), and its magnetic sensitivity characteristics are still significantly different from those of traditional in-plane anisotropic TMR, resulting in the limitation of TMR's out-of-plane magnetic field detection capability. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a tunnel magnetoresistive magnetic detector with out-of-plane magnetic field detection capability, which overcomes the problem of existing tunnel magnetoresistive magnetic detectors that are difficult to detect out-of-plane magnetic fields.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A tunnel magnetoresistance magnetic detector with out-of-plane magnetic field detection capability comprises a superconducting shielding layer, a first tunnel magnetoresistance and a second tunnel magnetoresistance, a differential amplifier and a signal acquisition system, wherein:

[0007] The superconducting shielding layer is a rectangular superconducting film structure, which uses the complete diamagnetism of the superconductor to change the direction of the external magnetic field perpendicular to the superconducting shielding layer into a direction parallel to the superconducting shielding layer;

[0008] The first tunnel magnetoresistance and the second tunnel magnetoresistance are respectively located at edge regions on both sides above the superconducting shielding layer, have the same magnetic sensitivity direction and are parallel to the superconducting shielding layer;

[0009] The differential amplifier is used to amplify the differential signal between the first tunnel magnetoresistance and the second tunnel magnetoresistance;

[0010] The signal acquisition system is used to acquire and process the amplified differential signal of the first tunnel magnetoresistance and the second tunnel magnetoresistance.

[0011] Furthermore, the outputs of the first tunnel magnetoresistance and the second tunnel magnetoresistance are respectively connected to two differential signal input terminals of a differential amplifier, and the output terminal of the differential amplifier is connected to a signal acquisition system.

[0012] Furthermore, the superconducting shielding layer is made of low-temperature superconducting materials such as niobium, niobium-titanium, and niobium-tin, or high-temperature superconducting materials such as yttrium-barium-copper-oxide superconducting thin film materials.

[0013] Furthermore, the circuit structures of the first tunnel magnetoresistance and the second tunnel magnetoresistance both adopt a series structure of multiple tunnel junctions.

[0014] Furthermore, the sum of the sizes of the first tunnel magnetoresistance and the second tunnel magnetoresistance is smaller than the size of the superconducting shielding layer.

[0015] Furthermore, the magnetic field sensitivity of the first tunnel magnetoresistance and the second tunnel magnetoresistance in the vertical direction is adjusted by changing the size of the superconducting shielding layer.

[0016] The beneficial effects of the present invention are:

[0017] The tunnel magnetoresistance magnetic detector with out-of-plane magnetic field detection capability proposed in the present invention can convert the vertical magnetic field into the horizontal direction through a superconducting shielding layer, so that the tunnel magnetoresistance has the vertical magnetic field detection capability, and the magnetic field sensitivity of the tunnel magnetoresistance in the vertical direction can be adjusted by changing the size of the superconducting shielding layer, thereby solving the problem of the existing tunnel magnetoresistance that it is difficult to detect the out-of-plane magnetic field; in addition, the present invention adopts the differential output form of two tunnel magnetoresistances, avoiding the magnetic field interference in the in-plane direction, and thus can be used for tunnel magnetoresistance detection arrays and micro-area detection probes. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A top view of a tunnel magnetoresistive magnetic detector having out-of-plane magnetic field detection capability according to the present invention;

[0019] Figure 2 It is a simulation schematic diagram of a tunnel magnetoresistive magnetic detector with out-of-plane magnetic field detection capability according to the present invention. DETAILED DESCRIPTION

[0020] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms, and the present disclosure should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0021] like Figure 1 As shown, the tunnel magnetoresistance magnetic detector with out-of-plane magnetic field detection capability comprises: a superconducting shielding layer 1, a first tunnel magnetoresistance 2 and a second tunnel magnetoresistance 3, a differential amplifier 4 and a signal acquisition system 5, wherein the superconducting shielding layer 1 is composed of a rectangular superconducting film. In this embodiment, the rectangular superconducting film is 100 microns long, 100 microns wide and 1 micron thick, and its function is to use the complete anti-magnetism of the superconductor to repel the external magnetic field on the surface of the superconducting shielding layer 1 perpendicular to the rectangular superconducting film to the edge, and change the direction of the external magnetic field to a direction parallel to the rectangular superconducting film; the first tunnel magnetoresistance 2 and the second tunnel magnetoresistance 3, are respectively located at the edge areas on both sides above the superconducting shielding layer 1, and their sizes are smaller than the superconducting shielding layer 1. In this embodiment, the length, width and height of the first tunnel magnetoresistance 2 are 50 microns, 20 microns and 1 micron respectively, and the magnetic sensitive direction is parallel to the rectangular superconducting film plane of the superconducting shielding layer 1, and is used to detect the magnetic field intensity parallel to the direction of the superconducting shielding layer 1. The structure of the second tunnel magnetoresistance 3 is the same as that of the first tunnel magnetoresistance 2; the differential amplifier 4 is used to amplify the differential signal of the first tunnel magnetoresistance 2 and the second tunnel magnetoresistance 3; the signal acquisition system 5 is used to collect and process the voltage differential signal of the two tunnel magnetoresistances after amplification.

[0022] In the above detector, the voltage output signals of the first tunnel magnetoresistance 2 and the second tunnel magnetoresistance 3 are respectively connected to two differential signal input terminals of a differential amplifier 4 , and the output terminal of the differential amplifier 4 is connected to a signal acquisition system 5 .

[0023] In one embodiment, the superconducting shielding layer 1 can be made of low-temperature superconducting materials such as niobium, niobium titanium, niobium tin, or high-temperature superconducting materials such as yttrium barium copper oxide. The circuit structure of the first tunnel magnetoresistance 2 and the second tunnel magnetoresistance 3 adopts a series structure of multiple tunnel junctions.

[0024] Figure 2The working principle of the magnetic detector is as follows: when there is an external magnetic field B0 in the z direction, the external magnetic field reaches the surface of the superconducting shielding layer 1. Since the superconductor has complete anti-magnetism, the magnetic lines of force will be repelled to the edge on the surface of the superconducting shielding layer 1, and generate equal and opposite magnetic field components B1 in the horizontal direction (x direction) at the two opposite edges of the superconducting shielding layer 1, and are sensed by the first tunnel magnetoresistance 2 and the second tunnel magnetoresistance 3. The signals of the first tunnel magnetoresistance 2 and the second tunnel magnetoresistance 3 are amplified by the differential amplifier 4 and received by the signal acquisition system 5, so that the detector has the ability to detect magnetic fields in the vertical direction (z direction).

[0025] The technical solution of the embodiment of the present invention utilizes the characteristic that the superconductor has complete anti-magnetism in the superconducting state, so that the direction of the external magnetic field can be changed. At the same time, the first tunnel magnetoresistance 2 and the second tunnel magnetoresistance 3 are placed above the superconductor, so as to realize the magnetic field detection capability in the vertical direction. Since the first tunnel magnetoresistance 2 and the second tunnel magnetoresistance 3 have the advantages of small size and high spatial resolution, after adding the superconducting shielding layer 1, the spatial resolution of the first tunnel magnetoresistance 2 and the second tunnel magnetoresistance 3 will not be affected; at the same time, the magnetic field sensitivity of the first tunnel magnetoresistance 2 and the second tunnel magnetoresistance 3 in the vertical direction can be adjusted by changing the size of the superconducting shielding layer 1, and the magnetic field resolution of the tunnel magnetoresistance in the vertical direction is effectively improved, thereby overcoming the problem of the existing tunnel magnetoresistance magnetic detector that it is difficult to detect the magnetic field in the out-of-plane direction, and the first tunnel magnetoresistance 2 and the second tunnel magnetoresistance 3 adopt a differential output form to avoid magnetic field interference in the in-plane direction.

[0026] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0027] Although the present invention has been described according to a limited number of embodiments, it will be apparent to those skilled in the art, with the benefit of the above description, that other embodiments may be envisioned within the scope of the invention thus described. In addition, it should be noted that the language used in this specification is primarily selected for readability and instructional purposes, rather than for the purpose of explaining or limiting the subject matter of the present invention.

Claims

1. A tunnel magnetoresistive magnetic detector with out-of-plane magnetic field detection capability, characterized in that: It includes a superconducting shielding layer, a first tunnel magnetoresistance, a second tunnel magnetoresistance, a differential amplifier and a signal acquisition system, wherein: The superconducting shielding layer is a rectangular superconducting film structure, which uses the complete diamagnetism of the superconductor to change the direction of the external magnetic field perpendicular to the superconducting shielding layer into a direction parallel to the superconducting shielding layer; The first tunnel magnetoresistance and the second tunnel magnetoresistance are respectively located at edge regions on both sides above the superconducting shielding layer, have the same magnetic sensitivity direction and are parallel to the superconducting shielding layer; The differential amplifier is used to amplify the differential signal between the first tunnel magnetoresistance and the second tunnel magnetoresistance; The signal acquisition system is used to acquire and process the amplified differential signal of the first tunnel magnetoresistance and the second tunnel magnetoresistance.

2. The tunnel magnetoresistive magnetic detector with out-of-plane magnetic field detection capability according to claim 1, characterized in that: The outputs of the first tunnel magnetoresistance and the second tunnel magnetoresistance are respectively connected to two differential signal input terminals of a differential amplifier, and the output terminal of the differential amplifier is connected to a signal acquisition system.

3. The tunnel magnetoresistive magnetic detector with out-of-plane magnetic field detection capability according to claim 1, characterized in that: The superconducting shielding layer is made of low-temperature superconducting materials such as niobium, niobium-titanium, and niobium-tin, or high-temperature superconducting materials such as yttrium-barium-copper-oxide superconducting thin film materials.

4. The tunnel magnetoresistive magnetic detector with out-of-plane magnetic field detection capability according to claim 1, characterized in that: The circuit structures of the first tunnel magnetoresistance and the second tunnel magnetoresistance both adopt a series structure of multiple tunnel junctions.

5. The tunnel magnetoresistive magnetic detector with out-of-plane magnetic field detection capability according to claim 1, characterized in that: The sum of the sizes of the first tunnel magnetoresistance and the second tunnel magnetoresistance is smaller than the size of the superconducting shielding layer.

6. The tunnel magnetoresistive magnetic detector with out-of-plane magnetic field detection capability according to claim 1, characterized in that: The magnetic field sensitivity of the first tunnel magnetoresistance and the second tunnel magnetoresistance in the vertical direction is adjusted by changing the size of the superconducting shielding layer.

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