CN111044952A - Magnetic sensor - Google Patents
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- CN111044952A CN111044952A CN201911215140.XA CN201911215140A CN111044952A CN 111044952 A CN111044952 A CN 111044952A CN 201911215140 A CN201911215140 A CN 201911215140A CN 111044952 A CN111044952 A CN 111044952A
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Abstract
The present invention provides a magnetic sensor comprising: the magneto-resistance sensing unit is of a topological insulator and ferromagnetic metal double-layer thin film structure; or the magneto-resistance sensing unit is of a double-layer film structure of the Peltier metal and the ferromagnetic metal; the magnetic resistance sensing unit is configured to be connected with current along the direction of the maximum outer contour of the magnetic resistance sensing unit, and the magnetic moment of the magnetic resistance sensing unit is biased by 45 degrees through an equivalent magnetic field under the coupling action of Rashba spin orbits; the substrate and the insulating layer form a package for the magnetoresistive sensing unit. The magnetic sensor formed by at least one magneto-resistance sensing unit has the characteristics of simple structure, easiness in preparation and good uniformity, and the bias field can be adjusted by current, so that the adjustment process of magnetic moment bias is greatly simplified. Meanwhile, the magnetic sensor can generate a strong Rashba magneto-resistance effect, and the detection sensitivity of the device can be obviously improved.
Description
Technical Field
The invention relates to the technical field of magnetic materials and components, in particular to a magnetic sensor.
Background
The magnetic sensor is widely applied to the fields of aerospace, automobiles, industry, consumption, military and the like. The magnetoresistance refers to the phenomenon that the resistance of a material changes under the action of an external magnetic field, and the magnetoresistance sensor is a device for converting various magnetic fields and the change quantity thereof into electric signals to be output. The sensor based on the magnetoresistance effect is gradually entering the magnetic sensor market due to the characteristics of high sensitivity, small volume, low power consumption, easy integration and the like, wherein the magnetic sensor based on the Anisotropic Magnetoresistance (AMR) is already applied in a large scale.
At present, in order to make the magneto-resistance sensor work in a linear region and improve the sensitivity and the dynamic range, a magnetic bias technology is needed to be used, and the corresponding magnetic bias is realized by a complicated process or a film layer structure. The most commonly used magnetic biasing techniques are the soft magnetic adjacent layer (SAL) biasing technique and the babber electrode biasing technique. SAL biasing is implemented in a three-layer heterostructure of soft magnetic/insulating/probe layers, wherein the resistivity of the soft magnetic layer is much greater than that of the probe layer, an Oersted field generated by current in the probe layer causes biasing of the magnetic moment of the soft magnetic layer, and stray fields generated by the biasing of the magnetic moment in turn cause biasing of the magnetic moment of the probe layer. By optimizing the thickness of each layer and the magnetism of the soft magnetic layer and the detection layer, the included angle between the magnetic moment of the detection layer and the current can be 45 degrees, and high linearity and high sensitivity signal output are realized. Adding a soft magnetic layer, the total thickness of which easily exceeds 20nm, which reduces the sensitivity of the device; meanwhile, the bias field caused by stray field of the soft magnetic layer has the defect of non-uniformity. The Barber electrode biasing technology is characterized in that strip-shaped electrodes are covered on a ferromagnetic metal layer, the included angle between the long axis of each electrode and the magnetic moment of the ferromagnetic layer is 45 degrees, and the included angle between the current flowing direction between adjacent strips and the magnetic moment of the ferromagnetic layer is 45 degrees. Therefore, the Barber electrode structure needs to carry out photoetching preparation on the Barber electrode on the basis of the completion of magnetic thin film plating, a complex process is needed, the alignment precision is high, and meanwhile, the edge has the problem of non-uniformity. In addition, the magnitude of the anisotropic magnetoresistance in ferromagnetic metals is small, which results in low sensitivity of the magnetic sensor.
Therefore, it is necessary to introduce a new magnetic sensor to realize high-linearity and high-sensitivity signal output with a simple device structure, to promote miniaturization of the device, and to improve the integration of the device.
Disclosure of Invention
An object of the present invention is to provide a magnetic sensor, so as to solve the problems of the existing magnetic sensor, such as complicated structure and difficult adjustment of magnetic offset angle.
A magnetic sensor, comprising:
the magneto-resistance sensing unit is of a topological insulator and ferromagnetic metal double-layer thin film structure;
or the magneto-resistance sensing unit is of a double-layer film structure of the Peltier metal and the ferromagnetic metal;
the magnetic resistance sensing unit is configured to be connected with current along the direction of the maximum outer contour of the magnetic resistance sensing unit, and the magnetic moment of the magnetic resistance sensing unit is biased by 45 degrees through an equivalent magnetic field under the coupling action of Rashba spin orbits;
the substrate and the insulating layer form a package for the magnetoresistive sensing unit.
Optionally, the topological insulator is Bi2Se3、Bi2Te3、Sb2Te3、(BixSb1-x)2Te3A crystalline thin film of a material;
alternatively, the topological insulator is BiSexPolycrystalline or amorphous thin films of material.
Optionally, the exo-semimetal is WTe2、MoTe2、MoxW1-xTe2Single crystal, polycrystalline or amorphous thin films of material.
Optionally, the ferromagnetic metal is NixFe1-x，CoxFeyB1-x-y，NixCo1-x，NixFeyCo1-x-y，NixFeyMo1-x-yOr a Co material.
Optionally, the magnetoresistive sensing unit is formed by magnetron Sputtering (Sputtering) or Molecular Beam Epitaxy (MBE).
Optionally, the magnetic sensor is in a wheatstone bridge structure, each bridge arm of the wheatstone bridge structure is provided with at least one magneto-resistance sensing unit in the same number, and the connection direction of the magneto-resistance sensing units is the maximum outer contour direction.
Optionally, the shape of the magnetoresistive sensing unit is an ellipse or a rectangle.
Optionally, the material of the substrate is Si or SiO2。
Optionally, the insulating layer is Al2O3、SiNxOr SiO2。
The technical scheme of the invention has the beneficial effects that: the magnetic sensor formed by at least one magneto-resistance sensing unit has the characteristics of simple structure, easiness in preparation and good uniformity, and the bias field can be adjusted by current, so that the adjustment process of magnetic moment bias is greatly simplified; the magneto-resistance sensing unit is arranged into a topological insulator and ferromagnetic metal or a double-layer film structure of a half metal and a ferromagnetic metal, so that the structure of the magnetic sensor can be simplified, and the lightness and thinness of the magnetic sensor are promoted; meanwhile, the magnetic sensor can generate a strong Rashba-Edelstein magneto-resistance effect, and the detection sensitivity of the device can be obviously improved.
Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.
FIG. 1 is a schematic diagram of a magnetic sensor according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a magnetic sensor according to an embodiment of the present invention;
FIG. 3 shows Rashba equivalent field H in the magnetoresistive sensing unit according to an embodiment of the inventionFLA graph of variation with current density;
FIG. 4 shows a demagnetizing field H according to an embodiment of the present inventiondAccording to the change of the major axis a of the ellipseDrawing;
FIG. 5 is a graph of sensitivity as a function of magnetic sensor size and ferromagnetic metal saturation magnetization M according to an embodiment of the present inventionSA graph of variation relationships of (2);
fig. 6 is a magnetoresistive graph of the magnetoresistive sensing unit 1 and the magnetoresistive sensing unit 2 under different bias magnetic fields according to an embodiment of the invention;
FIG. 7 is a graph of magnetoresistive random field H under different bias fields according to an embodiment of the inventionyA graph of variation relationships of (2);
FIG. 8 is a graph of power consumption versus current density and ellipse major axis a for a magnetic sensor according to an embodiment of the present invention.
The figures are labeled as follows: 10-ferromagnetic metal; 20-topological insulator or epi semimetal.
Detailed Description
Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.
The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.
Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.
In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
In the prior art, in order to enable the magneto-resistance sensor to work in a linear region and improve the sensitivity and the dynamic range of the sensor, the used magnetic biasing technology mainly comprises a soft magnetic adjacent layer (SAL) biasing technology and a babber (Barber) electrode biasing technology, the two technologies relate to complex processes and film layer structures, and the problems of low sensitivity, uneven biasing field and the like exist at the same time. Therefore, in order to solve various problems of the existing magnetic bias technology, it is necessary to provide a magnetic sensor with easy implementation of the magnetic bias mode and simple manufacturing process.
The invention provides a magnetic sensor, comprising: the magneto-resistance sensing unit is of a topological insulator and ferromagnetic metal double-layer thin film structure; or the magneto-resistance sensing unit is of a double-layer film structure of the Peltier metal and the ferromagnetic metal; the magnetic resistance sensing unit is configured to be connected with current along the direction of the maximum outer contour of the magnetic resistance sensing unit, and the magnetic moment of the magnetic resistance sensing unit is biased by 45 degrees through an equivalent magnetic field under the coupling action of Rashba spin orbits; the substrate and the insulating layer form a package for the magnetoresistive sensing unit.
As an embodiment of the present invention, as shown in fig. 1, the magnetic sensor provided by the present invention includes a magnetoresistive sensing unit, and the magnetoresistive sensing unit is a two-layer thin film structure of a topological insulator 20 and a ferromagnetic metal 10. Wherein the topological insulator is an internal insulator, an outer layer or interface of materials that allow charge movement. The topological insulator and the ferromagnetic metal double-layer film heterostructure can generate a strong Rashba spin orbit coupling effect, so that a strong equivalent magnetic field can be generated to realize the bias of the magnetic moment of the ferromagnetic layer only by introducing a low-density current, and the topological insulator and ferromagnetic metal double-layer film heterostructure has the advantage of low energy consumption. Meanwhile, the double-layer film is simple in structure, the thickness and the uniformity of the film are easy to control, the magnetic sensor with small overall thickness can be processed, and the requirement for miniaturization of the sensor is met.
As another embodiment of the invention, as shown in FIG. 1, the magnetoresistive sensing unit according to the invention has a double-layer thin film structure of a half metal 20 and a ferromagnetic metal 10. The double-layer film heterostructure of the outer half metal and the ferromagnetic metal can generate a strong Rashba spin orbit coupling effect, so that a strong equivalent magnetic field can be generated to realize the bias of the magnetic moment of the ferromagnetic layer only by introducing a current with low density, and the double-layer film heterostructure has the advantage of low energy consumption. Meanwhile, the double-layer film is simple in structure, the thickness and the uniformity of the film are easy to control, the magnetic sensor with small overall thickness can be processed, and the requirement for miniaturization of the sensor is met.
Optionally, in the topological insulator and ferromagnetic metal double-layer film structure or the hall semi-metal and ferromagnetic metal double-layer film structure applied in the present invention, the positional relationship between the upper layer and the lower layer between the topological insulator or hall semi-metal and ferromagnetic metal is not limited, that is, the upper layer may be the topological insulator or hall semi-metal, the lower layer may be the ferromagnetic metal, or the upper layer may be the ferromagnetic metal, and the lower layer may be the topological insulator or hall semi-metal, which can be selected by those skilled in the art.
When current is led in the direction of the maximum outer contour of the magneto-resistance sensing unit, an equivalent magnetic field is generated in the magneto-resistance sensing unit under the action of Rashba spin orbit coupling effect, so that the magnetic moment of the magneto-resistance sensing unit is biased by 45 degrees. Rashba spin-orbit coupling refers to the band tilt in surface/interface systems due to structural inversion asymmetry.
The magnetic moment biasing principle of the magneto-resistance sensing unit is as follows: the magneto-resistance sensing unit forms a demagnetization field H along the direction of the maximum outer contour dimension according to the shape and the structure of the magneto-resistance sensing unitdAnd an anisotropy field HK. As an example, as shown in FIG. 1, demagnetizing field HdAnd an anisotropy field HKAnd overlapping along the X-axis direction. When current is led in the direction of the maximum outer contour dimension of the magneto-resistance sensing unit, an Oersted field H is generatedOeAnd an equivalent magnetic field H generated due to Rashba spin-orbit coupling effectFL. The Oster field HOeAnd an equivalent magnetic field HFLAnd overlapping along the Y-axis direction. The tangent value of the magnetic moment offset angle is the ratio of the magnetic field superposition result in the Y-axis direction and the magnetic field superposition result in the X-axis direction, i.e. the ratio
Wherein HdFor demagnetizationA field;
HKis an anisotropic field;
HFLis an equivalent magnetic field;
HOeis an oersted field.
The calculation formula of the magnetic moment offset angle can be used for adjusting the offset angle of the magnetic moment by adjusting the magnitude of each parameter.
The magnetic sensor also comprises a substrate and an insulating layer, and the magnetic sensor is obtained by packaging the magneto-resistance sensing unit by using the substrate and the insulating layer. The base serves as a substrate for the entire magnetic sensor, and the insulating layer serves as a protective layer.
The magnetic sensor structure provided by the invention can generate a strong Rashba spin orbit coupling effect only by introducing a small current, so that the angular bias of the magnetic moment is realized, and the magnetic sensor has high detection sensitivity. The magnetic sensor formed by at least one magneto-resistance sensing unit has the characteristics of simple structure, adjustable bias field and good uniformity, and simultaneously, the magneto-resistance sensing unit is designed into a double-layer film structure formed by a topological insulator or a Peltier half metal and a ferromagnetic metal, so that the problems of complex process and film structure in the existing magnetic biasing technology are solved, and the magnetic sensor is favorable for popularization and application.
Alternatively, as shown in FIG. 2, the magnetic sensor provided by the present invention is in a Wheatstone bridge configuration. And each bridge arm of the Wheatstone bridge is connected with the same number of magneto-resistance sensing units. Optionally, each bridge arm may include one magnetoresistive sensing unit, and the four magnetoresistive sensing units forming the wheatstone bridge have identical shapes and structures. The direction of the maximum outer contour size of the magneto-resistance sensing units is used as the connecting direction, and the four magneto-resistance sensing units are mutually connected to form a Wheatstone bridge. The Wheatstone bridge is a detection circuit, and has simple structure, high accuracy and high sensitivity. In the present invention, as can be seen from fig. 2, four magnetoresistive sensing units forming a wheatstone bridge are provided, wherein magnetoresistive sensing unit 1 is disposed opposite to magnetoresistive sensing unit 4, and magnetoresistive sensing unit 2 is disposed opposite to magnetoresistive sensing unit 3. When current is introduced into the Wheatstone bridge, the current flows along the direction of the maximum outer contour of each magneto-resistance sensing unit. Due to the Rashba spin orbit coupling effect, equivalent magnetic fields with the same size are generated in the four identical magneto-resistance sensing units, so that the magnetic moments of the magneto-resistance sensing units are biased by 45 degrees. The magnetic sensor which utilizes four identical magneto-resistance sensing units to form a Wheatstone bridge has higher sensitivity. Optionally, two or more magnetoresistive sensing units may be connected to each arm of the wheatstone bridge, which is not limited by the present invention.
Optionally, the topological insulator is Bi2Se3、Bi2Te3、Sb2Te3、(BixSb1-x)2Te3A crystalline thin film of a material; alternatively, the topological insulator is BiSexPolycrystalline or amorphous thin films of material.
As an embodiment of the present invention, Bi can be selected as the topological insulator2Se3、Bi2Te3、Sb2Te3、(BixSb1-x)2Te3The single crystal thin film of these materials may be BiSexPolycrystalline or amorphous thin films of material. Of course, the topological insulator of the present invention may also be other topological insulator materials, or materials with the same or similar properties to the topological insulator material, and the present invention is not limited thereto, and those skilled in the art can select the topological insulator according to the requirements and the difficulty level of obtaining the materials. The topological insulator has various kinds of selection, and simultaneously, the single crystal, polycrystal or amorphous state of the material can meet the performance requirement of the magnetic sensor, thereby reducing the manufacturing cost of the magnetic sensor virtually and facilitating the popularization and the application of the magnetic sensor.
Optionally, the exo-semimetal is WTe2、MoTe2、MoxW1-xTe2Single crystal, polycrystalline or amorphous thin films of material.
As an embodiment of the present invention, the exo-semimetal may be WTE2、MoTe2、MoxW1-xTe2Single crystal, polycrystalline or amorphous films of these materials. Of course, the semimetal of the present invention may be other materials which may or may not be found to be the same as the semimetal, or may be materials having the same or similar properties to the semimetal. The field semimetal has various types, and simultaneously, the single crystal, polycrystal or amorphous state of the material can meet the performance requirement of the magnetic sensor, thereby reducing the manufacturing cost of the magnetic sensor virtually and facilitating the popularization and the application of the magnetic sensor.
Alternatively, the ferromagnetic metal forming the magnetoresistive sensing cell of the present invention may be NixFe1-x，CoxFeyB1-x-y，NixCo1-x，NixFeyCo1-x-y，NixFeyMo1-x-yOr Co, or other ferromagnetic metal materials, which is not limited in the present invention. The magneto-resistance sensing unit made of the ferromagnetic metal material can generate a stronger Rashba spin orbit coupling effect when current is introduced, and magnetic moment bias is easier to realize.
Optionally, the magnetoresistive sensing unit is formed by magnetron Sputtering (Sputtering) or Molecular Beam Epitaxy (MBE).
Specifically, the magnetoresistive sensing unit of the invention is a double-layer film structure, which can be a double-layer film structure formed by a topological insulator and a ferromagnetic metal, and can also be a double-layer film structure formed by a semimetal and a ferromagnetic metal. As one example, the two-layer film structure of the present invention may be formed using a magnetron Sputtering (Sputtering) process. Magnetron Sputtering (Sputtering) is one kind of Physical Vapor Deposition (PVD), and has the working principle that electrons collide with argon atoms in the process of flying to a substrate under the action of an electric field to ionize the argon atoms to generate argon positive ions and new electrons, the new electrons fly to the substrate, the argon ions accelerate to fly to a cathode target under the action of the electric field, and the surface of the cathode target is bombarded at high energy to sputter the target. In the sputtered particles, neutral target atoms or molecules are deposited on the substrate to form a thin film. The topological insulator and ferromagnetic metal or exol semimetal and ferromagnetic metal double-layer film structure is prepared by utilizing a magnetron sputtering technology, and has the advantages of simple equipment, easiness in control, large film coating area, strong adhesive force and the like.
As another example, the bilayer film structure of the present invention may be formed using Molecular Beam Epitaxy (MBE) techniques. Molecular Beam Epitaxy (MBE) is similar to vacuum evaporation plating, and is a method for preparing a single crystal film by ejecting each component constituting a crystal and atoms (molecules) to be doped from an ejection furnace onto a substrate at a certain thermal movement rate and in a certain proportion under an ultrahigh vacuum condition to perform epitaxial growth of the crystal. As an example, a topological insulator film can be epitaxially grown on a substrate, and then a ferromagnetic metal film can be formed on the topological insulator film by molecular beam epitaxy. The magneto-resistance sensing unit film is formed by utilizing a molecular beam epitaxial growth technology, so that the pollution of gas to a film layer can be reduced, and the surface of the film layer is kept highly clean; in addition, the growth temperature of the film layer is low, so that the temperature resistance requirement on equipment is favorably reduced, and the energy loss can be reduced; the thickness, components and impurity concentration of the film layer can be accurately controlled; the film layer with a larger area can be obtained by utilizing the epitaxial growth technology, the flatness of the surface of the film layer can reach the atomic level, and the influence of the surface flatness on the performance of the magnetic sensor is reduced.
In the invention, the double-layer film structure formed by magnetron Sputtering (Sputtering) has higher film forming efficiency compared with the Molecular Beam Epitaxy (MBE) technology. Therefore, the magnetoresistive sensing units are preferably shaped by magnetron Sputtering (Sputtering) technology.
Optionally, the shape of the magnetoresistive sensing unit is a thin film with an oval or rectangular shape. The shape of the magneto-resistance sensing unit is set to be a regular ellipse or a rectangle, so that the flowing direction of current is convenient to select, the magneto-resistance sensing unit is beneficial to batch production, and the preparation efficiency of the magnetic sensor is improved. Of course, the magnetoresistive sensing units may be arranged in other regular or irregular shapes, and those skilled in the art can select them according to actual needs, and the invention is not limited thereto.
Optionally, the substrate is Si or SiO2(ii) a The insulating layer is Al2O3、SiNxOr SiO2。
Specifically, the substrate of the magnetic sensor is Si or SiO2A material for molding a magnetoresistive sensing cell thereon. The insulating layer is made of Al2O3、SiNxOr SiO2Since the magnetoresistance sensing unit is easily oxidized, the double-layer film structure of the magnetoresistance sensing unit is encapsulated using the insulating layer, which constitutes a protective layer to prevent the magnetoresistance sensing unit from being oxidized.
In one embodiment of the present invention, a magnetic sensor is manufactured as follows: firstly, forming a topological insulator and a ferromagnetic metal or a semimetal and ferromagnetic metal double-layer film by utilizing a magnetron Sputtering (Sputtering) or Molecular Beam Epitaxy (MBE) process; then, micro-nano processing is carried out on the double-layer film, the processing procedure comprises the steps of etching the shape of the magneto-resistance sensing unit by using an ultraviolet photoetching mode, and etching by adopting an argon ion etching mode to obtain the required shape; then, carrying out second photoetching on the magneto-resistance sensing unit with the required shape, and etching the position of an electrode; then growing on the position of the electrode to obtain an electrode connected with an external circuit, wherein the material of the electrode can be Au or Cu; then washing off photoresist on the magnetoresistance sensing unit; and finally, packaging by using packaging materials. The skilled person can also choose to make the magnetic sensor of the present invention in other ways, which the present invention is not limited to.
The technical scheme of the invention has the beneficial effects that: the magnetic sensor with the Wheatstone bridge structure is formed by at least one magneto-resistance sensing unit, has the characteristics of simple structure, adjustable bias field through current and good uniformity, and can generate stronger Rashba-Edelstein magneto-resistance effect in a topological insulator and ferromagnetic metal or double-layer film heterostructure of the foreign metal and the ferromagnetic metal, thereby obviously improving the detection sensitivity of the device.
The following provides a preferred embodiment of the present invention to specifically explain the performance of the magnetic sensor.
Selecting Bi2Se3And a NiFe double-layer film structure is used as a test sample, the thickness of the two layers of films is in the nanometer level, the shapes of the two layers of films are oval, the major axis is a, the minor axis is b, and the value of a/b is 2-10. Optionally, the maximum outer contour dimension a of the magnetoresistive sensing unit is 10-1000 μm. When current is introduced along the long axis direction, the Rashba effect generates an equivalent magnetic field in the ferromagnetic metal, so that the magnetic moment is biased. Optionally, the current density led into the magnetic resistance sensing unit is 104～107A/cm2。
The current density versus equivalent magnetic field strength is shown in fig. 3. In the figure, three lines from top to bottom represent that the saturation magnetization Ms is 300, 400, 500emu/cm3. As can be seen from the figure, the equivalent magnetic field HFLStrength and introduction of Bi2Se3The current density in (1) is linear. The larger the saturation magnetization at the same current density, the larger the equivalent magnetic field HFLThe smaller. The linear behavior of the sensor can thus be achieved by using the spin orbit torque effective field.
In fig. 4 is shown the demagnetizing field HdThe relationship varies with the major axis a of the ellipse. As can be seen from the figure, the demagnetizing field HdIn linear relation to the major axis a of the ellipse, HdDecreases with increasing a. Meanwhile, under the condition of the same ellipse major axis and saturation magnetization Ms, the larger the ratio a/b of the major axis to the minor axis is, the larger the demagnetization field HdThe greater the intensity of (a); under the same ellipse long axis and ratio of long axis to short axis, the larger saturation magnetization Ms, the larger demagnetization field HdThe greater the intensity of (c). It can be seen that the demagnetizing field HdIs related to the size of the thin film of the magnetoresistive sensing cell and the saturation magnetization Ms. The demagnetizing field H can be adjusted by changing the film size and saturation magnetization Ms of the magnetoresistive sensing unitdThe strength of (2).
The sensitivity is shown in FIG. 5 as a function of the magnetic sensor size and ferromagnetic metal saturation magnetization MSThe variation relationship of (a). Given the ratio of the major to minor axes of the ellipse is 4, it can be seen that the sensitivity of the sensor increases with increasing major axis. Sensitivity dependent on saturation magnetization M of ferromagnetic metalsSIncreasing and decreasing. When the surface area of the bilayer membrane structure is constant,saturation magnetization MSIncreasing with increasing ferromagnetic metal layer thickness. Therefore, the sensitivity of the magnetic sensor can be controlled by adjusting the size of the double-layer thin film and the thickness of the ferromagnetic metal layer. According to the embodiment of the invention, the regulation and control range of the sensitivity obtained from the graph is 500-1300 m omega/Oe.
The magnetoresistive curves of the magnetoresistive sensing unit 1 and the magnetoresistive sensing unit 2 in the wheatstone bridge under different bias magnetic fields are shown in fig. 6. Wherein a/b is 4, Ms is 400emu/cm3. Shown are different bias angles and equivalent magnetic field HFLMagnetoresistive curve of (1). When H is presentFLWhen it is + -1.78 Oe (in this case Bi)2Se3The current in the layer induced an Oersted field in the NiFe layer of 0.12Oe, the sum of the demagnetizing field and the anisotropy field Hd+Hk1.9Oe) the offset angle is 45 °. As can be seen from fig. 7, under the above conditions, the sensitivity of the magnetic sensor is the highest, and the corresponding linearity is maximized.
Fig. 8 shows a graph of power consumption of a magnetic sensor as a function of current density and major axis a of the ellipse. Wherein, the ratio of the major axis and the minor axis of the ellipse is determined and is 4. As can be seen, the power consumption P (W) of the magnetic sensor is a function of the current density jBS(A/cm 2) and increases with the ellipse major axis a, which can be summarized by controlling the ellipse major axes a and jBSCan control the power consumption of the magnetic sensor.
In summary, the sensitivity and power of the magnetic sensor can be adjusted by adjusting the shape and size of the sensor unit; meanwhile, 45-degree bias of magnetic moment and current can be realized through regulating the control of the current density.
The magnetic sensor provided by the invention has the advantages of simple structure and convenience in adjustment of the magnetic moment offset angle, and can realize detection with high linearity and high sensitivity.
Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.
Claims (9)
1. A magnetic sensor, comprising:
the magneto-resistance sensing unit is of a topological insulator and ferromagnetic metal double-layer thin film structure;
or the magneto-resistance sensing unit is of a double-layer film structure of the Peltier metal and the ferromagnetic metal;
the magnetic resistance sensing unit is configured to be connected with current along the direction of the maximum outer contour of the magnetic resistance sensing unit, and the magnetic moment of the magnetic resistance sensing unit is biased by 45 degrees through an equivalent magnetic field under the coupling action of Rashba spin orbits;
the substrate and the insulating layer form a package for the magnetoresistive sensing unit.
2. Magnetic sensor according to claim 1, characterized in that the topological insulator is Bi2Se3、Bi2Te3、Sb2Te3、(BixSb1-x)2Te3A crystalline thin film of a material;
alternatively, the topological insulator is BiSexPolycrystalline or amorphous thin films of material.
3. The magnetic sensor of claim 1, wherein the outer half-metal is WTe2、MoTe2、MoxW1- xTe2Single crystal, polycrystalline or amorphous thin films of material.
4. Magnetic sensor according to claim 1, characterized in that the ferromagnetic metal is NixFe1-x、CoxFeyB1-x-y、NixCo1-x、NixFeyCo1-x-y、NixFeyMo1-x-yOr a Co material.
5. The magnetic sensor according to claim 1, wherein the magnetoresistive sensing units are shaped by magnetron Sputtering (Sputtering) or Molecular Beam Epitaxy (MBE).
6. The magnetic sensor according to claim 1, wherein the magnetic sensor is a wheatstone bridge structure, each arm of the wheatstone bridge structure has at least one magneto-resistive sensing unit with the same number, and the connection direction of the magneto-resistive sensing units is the direction of the largest outer contour.
7. Magnetic sensor according to claim 1, characterized in that the magnetoresistive sensing units are oval or rectangular in shape.
8. Magnetic sensor according to claim 1, characterized in that the material of the substrate is Si or SiO2。
9. The magnetic sensor of claim 1, wherein the insulating layer is Al2O3、SiNxOr SiO2。
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113341354A (en) * | 2021-04-29 | 2021-09-03 | 北京航空航天大学 | Three-axis magnetic resistance magnetic field sensor and manufacturing method thereof |
| CN113466759A (en) * | 2021-06-30 | 2021-10-01 | 山东大学 | Single-axis and double-axis magnetic resistance magnetic field sensor and manufacturing method |
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