Magnetoresistor with in-layer electron channel and magneto-dependent sensor

Abstract

The invention relates to a magneto-resistor with an in-layer electron channel and a magneto-sensor, and the magneto-resistor comprises a first insulating ferromagnetic layer, a second insulating ferromagnetic layer, and a non-ferromagnetic composite conductive layer disposed between the first insulating ferromagnetic layer and the second insulating ferromagnetic layer. The thickness of the non-ferromagnetic composite conductive layer is nanoscale, the non-ferromagnetic composite conductive layer is composed of an upper conductive layer, a lower conductive layer and an electron channel layer clamped between the upper conductive layer and the lower conductive layer, and the resistance of the electron channel layer is at least two orders of magnitude smaller than the resistance of the upper conductive layer and the resistance of the lower conductive layer. Different from a conventional magnetoresistor utilizing the giant magnetoresistance effect, whether ferromagnetic layers or non-ferromagnetic layers are made of metal materials, the non-ferromagnetic composite conductive layer is clamped between the two insulating ferromagnetic layers in the magnetoresistor, when the giant magnetoresistance effect occurs, current cannot be shunted by the two insulating ferromagnetic layers, and the magnetoresistance effect of the magnetoresistor is improved. The giant magnetoresistance effect is purer and more remarkable, and the magnetic sensitivity is higher.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic sensitive sensors, and in particular to a magnetic sensitive resistor and a magnetic sensitive sensor with an intra-layer electron channel. Background Art

[0002] The resistance of a magnetoresistor changes with the change of the magnetic field, that is, it can change its resistance under the action of an external magnetic field (including changes in the strength or direction of the magnetic field). Traditional magnetoresistors are usually made of semiconductor materials with high electron mobility and magnetic sensitivity. Commonly used semiconductors include InSb (or InSb-NiSb eutectic material), indium arsenide (InAs) and gallium arsenide (GaAs). For example, in a rectangular semiconductor InSb sheet, when a current passes along the length direction, if a magnetic field is applied in the direction perpendicular to the width of the current sheet, the resistivity of the semiconductor InSb sheet will increase in the length direction.

[0003] The stability and sensitivity of traditional magnetoresistors based on semi-conductive materials are usually not as good as those of metal thin film magnetoresistors developed later. Metal thin film magnetoresistors use the giant magnetoresistance effect or tunneling magnetoresistance effect of materials: magnetoresistors with giant magnetoresistance effect are generally multi-layer metal film structures composed of alternating ferromagnetic and non-ferromagnetic metal materials; magnetoresistors with tunneling magnetoresistance effect usually have a "sandwich structure" consisting of two ferromagnetic metal electrode film layers and an insulating barrier layer sandwiched in the middle. The generation of the above two effects is related to the electron spin in the material. When the magnetic moments of the two ferromagnetic layers are parallel to each other, the scattering and polarization of electrons related to spin are the smallest, so the resistance of the material is also small. When the magnetic moments of the two ferromagnetic layers are antiparallel, the scattering and polarization related to spin are the strongest, and the resistance of the material is the largest. However, for giant magnetoresistance magnetoresistors, since both the ferromagnetic layer and the non-ferromagnetic layer are conductive metals, the electrons are distributed in a considerable amount in both the magnetic layer and the non-magnetic layer, which will lead to a weakening of the giant magnetoresistance effect and a reduction in sensitivity. Summary of the invention

[0004] The present invention provides a magnetoresistor and a magnetoresistive sensor with an intralayer electron channel, aiming to overcome the technical problem that the magnetoresistive resistor based on the giant magnetoresistance effect in the prior art has the problem that both the ferromagnetic layer and the non-ferromagnetic layer are conductive metals, so when conducting electricity, electrons are distributed in a considerable amount in the magnetic layer and the non-magnetic layer, which will lead to a weakening of the giant magnetoresistance effect and a reduction in sensitivity.

[0005] The technical solution of the present invention to solve the above technical problems is as follows: a magnetoresistor with an intra-layer electron channel, which includes a first insulating ferromagnetic layer, a second insulating ferromagnetic layer and a non-ferromagnetic composite conductive layer arranged between the first insulating ferromagnetic layer and the second insulating ferromagnetic layer, the thickness of the non-ferromagnetic composite conductive layer is nanometer scale and is composed of an upper conductive layer, a lower conductive layer and an electron channel layer sandwiched between the upper conductive layer and the lower conductive layer, and the resistance of the electron channel layer is at least two orders of magnitude smaller than the resistance of the upper conductive layer and the lower conductive layer.

[0006] Based on the above technical solution, the present invention can also be improved as follows.

[0007] Furthermore, the insulating ferromagnetic material used in the first insulating ferromagnetic layer and the second insulating ferromagnetic layer is a ferromagnetic and insulating metal oxide.

[0008] Furthermore, the metal oxide includes ferroferric oxide, barium ferrite or strontium ferrite.

[0009] Furthermore, the first insulating ferromagnetic layer is a reference layer with a fixed magnetization direction, the second insulating ferromagnetic layer is a free layer with a magnetization direction that can be changed by an external magnetic field, and the non-ferromagnetic composite conductive layer is a magnetic detection layer with a resistance that can be changed by an external magnetic field.

[0010] Furthermore, the upper conductive layer and the lower conductive layer are metal film layers formed of any one of copper, silver, gold or platinum.

[0011] Furthermore, the thickness of the metal film layer is 1-20 nm.

[0012] Furthermore, the non-ferromagnetic conductive material used in the electron channel layer is graphene or nitrogen-doped graphene.

[0013] Furthermore, the thickness of the electron channel layer is 0.5-1.5 nm.

[0014] The present invention also provides a magnetic sensitive sensor, which comprises the above-mentioned magnetic sensitive resistor.

[0015] Furthermore, it also includes a substrate layer on the upper surface of which the second insulating ferromagnetic layer is formed, a protective layer covering the upper surface of the first insulating ferromagnetic layer, and electrodes electrically connected to the non-ferromagnetic composite conductive layer at both ends.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] Different from the structural feature that both the ferromagnetic layer and the non-ferromagnetic layer in the conventional magnetoresistive effect magnetoresistive resistor are made of metal, a non-ferromagnetic composite conductive layer is sandwiched between the two insulating ferromagnetic layers in the magnetoresistive resistor of the present invention. With such a design, on the one hand, the two insulating ferromagnetic layers are insulating materials, and there are almost no free electrons therein, so when conducting, the spin electron transfer is mainly concentrated in the middle non-ferromagnetic composite conductive layer, and the spin electrons are basically not scattered to the two insulating ferromagnetic layers. When the giant magnetoresistive effect occurs, the current will not be shunted by the two insulating ferromagnetic layers, and the giant magnetoresistive effect is purer and more significant, and the magnetic sensitivity is higher; on the other hand, the non-ferromagnetic composite conductive layer is nanometer-scale and the resistance of the electron channel layer located in the middle is significantly lower than that of the upper and lower conductive layers, so when power is turned on, the spin electrons are mainly concentrated in the electron channel layer with better permeability, and the upper and lower conductive layers play a moderate interception effect of avoiding the spin electrons from scattering to the two insulating ferromagnetic layers, and at the same time, the spin electrons in the nanometer-scale non-ferromagnetic composite conductive layer can be more significantly affected by the two insulating ferromagnetic layers, so that the magnetoresistive effect is higher and the sensitivity is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A front view of a magnetoresistor with an intralayer electron channel provided by the present invention;

[0019] Figure 2 The present invention provides Figure 1 An axonometric view of a magnetic sensor of a magnetic resistor shown;

[0020] Figure 3 for Figure 2 Schematic diagram of the enlarged structure within the dotted circle A.

[0021] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0022] 1. First insulating ferromagnetic layer; 2. Second insulating ferromagnetic layer; 3. Non-ferromagnetic composite conductive layer; 4. Upper conductive layer; 5. Lower conductive layer; 6. Electron channel layer; 7. Substrate layer; 8. Protective layer; 9. Electrode. DETAILED DESCRIPTION

[0023] The principles and features of the present invention are described below in conjunction with the accompanying drawings and specific embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0024] In the description of the present invention, if terms indicating orientation such as "up", "down", "left", "right", "top", "bottom", "inside" and "outside" are used, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0025] like Figure 1 As shown, the present invention provides a magnetoresistor with an intralayer electron channel, which includes a first insulating ferromagnetic layer 1, a second insulating ferromagnetic layer 2, and a non-ferromagnetic composite conductive layer 3 arranged between the first insulating ferromagnetic layer 1 and the second insulating ferromagnetic layer 2. The thickness of the non-ferromagnetic composite conductive layer 3 is nanometer scale and is composed of an upper conductive layer 4, a lower conductive layer 5, and an electron channel layer 6 sandwiched between the upper conductive layer 4 and the lower conductive layer 5. The resistance of the electron channel layer 6 is at least two orders of magnitude smaller than the resistance of the upper conductive layer 4 and the lower conductive layer 5.

[0026] It should be noted that, in the present invention, the thickness of the non-ferromagnetic composite conductive layer is in the nanometer scale, which means that the thickness is between 1-100 nm, preferably 1-30 nm.

[0027] In one embodiment of the present invention, the insulating ferromagnetic material used in the first insulating ferromagnetic layer 1 and the second insulating ferromagnetic layer 2 is a ferromagnetic and insulating metal oxide. Preferably, the metal oxide includes ferroferric oxide, barium ferrite or strontium ferrite. It should be noted that there are many kinds of insulating and ferromagnetic metal oxides, and those skilled in the art can make flexible choices when necessary, such as LaFe5O 12 、GdFe5O 12 、HoFe5O 12 、DyFe5O 12 、LuFe5O 12 , MgFe2O4, MnFe2O4, CuFe2O4, ZnFe2O4, CoFe2O4 and NiFe2O4, etc.

[0028] In one embodiment of the present invention, the first insulating ferromagnetic layer 1 is a reference layer with a fixed magnetization direction, the second insulating ferromagnetic layer 2 is a free layer with a magnetization direction that can be changed by an external magnetic field, and the non-ferromagnetic composite conductive layer 3 is a magnetic detection layer with a resistance that is changed by an external magnetic field.

[0029] It can be understood that the roles of the first insulating ferromagnetic layer and the second insulating ferromagnetic layer can be switched, that is, the second insulating ferromagnetic layer can be a reference layer with a fixed magnetization direction, and the first insulating ferromagnetic layer can be a free layer with a magnetization direction that can be changed by an external magnetic field. The magnetization direction of the fixed layer is fixed, and the magnetization direction of the free layer is easily changed by an external magnetic field. The magnetization of the free layer generally has two relatively stable orientations, which are parallel or anti-parallel to the reference layer. When the magnetic moments of the free layer and the fixed layer are parallel to each other, the spin electrons in the non-ferromagnetic composite conductive layer between the two layers are less scattered, so they can be transmitted more smoothly in a specific direction, so the resistance is smaller and the current is larger. When the magnetization direction of the free layer is reversed by the external magnetic field, that is, it is anti-parallel to the reference layer, the spin electrons in the non-ferromagnetic composite conductive layer between the two layers are scattered significantly, and the difficulty of transmission in a specific direction is also significantly increased, that is, the effect of significantly increased magnetoresistance is shown.

[0030] In one embodiment of the present invention, the upper conductive layer 4 and the lower conductive layer 5 are metal film layers formed of any one of copper, silver, gold or platinum, and the thickness of the metal film layer is preferably 1-20nm, and the best is 1-5nm. The non-ferromagnetic conductive material used in the electron channel layer 6 is graphene or nitrogen-doped graphene, and the thickness of the electron channel layer 6 is preferably 0.5-1.5nm, that is, the graphene or nitrogen-doped graphene is preferably a single layer or a few layers, so as to maintain its excellent conductive properties.

[0031] It should be noted that the thinner the metal film layer is, the better the sensitivity of the magnetoresistive sensor with a multilayer metal film structure and based on the tunnel magnetoresistance effect. However, when the metal film reaches the nanometer scale, the resistance of the metal film is generally large, which will cause the detection current to become smaller, thereby affecting the sensitivity of the magnetoresistive sensor. The present invention selects graphene or its dopants that still maintain excellent electrical conductivity at the nanometer scale as the electron channel layer material, and at the same time separates it from the first and second insulating ferromagnetic layers with nanometer-scale copper, silver and other metal films. The resistance of the metal film at the nanometer scale will be significantly greater than that of the graphene or its dopants at this scale, but the metal film at the nanometer scale is still a conductor. Relative to graphene or its dopants, the metal film at the nanometer scale is equivalent to forming a barrier layer between the electron channel layer and the first and second insulating ferromagnetic layers. Therefore, when conducting, the spin electron scattering effect is mainly concentrated in the electron channel layer, and a small amount exists in the nanometer-scale metal film layer, and will not be shunted to the first and second insulating ferromagnetic layers.

[0032] like Figure 2 and 3As shown, the present invention also provides a magnetic sensitive sensor, which includes the above-mentioned magnetic sensitive resistor, and the magnetic sensitive sensor also includes a substrate layer 7 on the upper surface of which the second insulating ferromagnetic layer 2 is formed, a protective layer 8 covering the upper surface of the first insulating ferromagnetic layer 1, and electrodes 9 electrically connected to the non-ferromagnetic composite conductive layer 3 at both ends.

[0033] It should be noted that the substrate layer and the protective layer are made of non-ferromagnetic materials, specifically, plastic films or plates such as PET, PVC, PC, etc., or ceramic films or plates. The first insulating ferromagnetic layer, the second insulating ferromagnetic layer, the upper conductive layer, the lower conductive layer, and the electron channel layer can be formed by using current chemical vapor deposition, physical vapor deposition, magnetron sputtering, etc., or more advanced film forming technology in the future.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A magnetoresistor having an intralayer electron channel, characterized in that: The invention comprises a first insulating ferromagnetic layer (1), a second insulating ferromagnetic layer (2), and a non-ferromagnetic composite conductive layer (3) arranged between the first insulating ferromagnetic layer (1) and the second insulating ferromagnetic layer (2); the thickness of the non-ferromagnetic composite conductive layer (3) is nanometer scale and it is composed of an upper conductive layer (4), a lower conductive layer (5), and an electron channel layer (6) sandwiched between the upper conductive layer (4) and the lower conductive layer (5); the resistance of the electron channel layer (6) is at least two orders of magnitude smaller than the resistance of the upper conductive layer (4) and the lower conductive layer (5).

2. A magnetoresistor with an intralayer electron channel according to claim 1, characterized in that: The insulating ferromagnetic material used in the first insulating ferromagnetic layer (1) and the second insulating ferromagnetic layer (2) is a ferromagnetic and insulating metal oxide.

3. A magnetoresistor with an intralayer electron channel according to claim 1, characterized in that: The metal oxide includes ferroferric oxide, barium ferrite or strontium ferrite.

4. A magnetoresistor with an intralayer electron channel according to claim 1, characterized in that: The first insulating ferromagnetic layer (1) is a reference layer with a fixed magnetization direction, the second insulating ferromagnetic layer (2) is a free layer with a magnetization direction that can be changed by an external magnetic field, and the non-ferromagnetic composite conductive layer (3) is a magnetic detection layer with a resistance that is changed by an external magnetic field.

5. The magnetoresistor with an intralayer electron channel according to claim 1, characterized in that: The upper conductive layer (4) and the lower conductive layer (5) are metal film layers formed of any one of copper, silver, gold or platinum.

6. A magnetoresistor with an intralayer electron channel according to claim 5, characterized in that: The thickness of the metal film layer is 1-20 nm.

7. A magnetoresistor with an intralayer electron channel according to any one of claims 1 to 6, characterized in that: The non-ferromagnetic conductive material used in the electron channel layer (6) is graphene or nitrogen-doped graphene.

8. A magnetoresistor with an intralayer electron channel according to claim 7, characterized in that: The thickness of the electron channel layer (6) is 0.5-1.5 nm.

9. A magnetic sensor, characterized in that: The magnetoresistor comprises the magnetoresistor according to any one of claims 1 to 8.

10. A magnetic sensor according to claim 9, characterized in that: It also includes a substrate layer (7) on the upper surface of which the second insulating ferromagnetic layer (2) is formed, a protective layer (8) covering the upper surface of the first insulating ferromagnetic layer (1), and electrodes (9) electrically connected to the non-ferromagnetic composite conductive layer (3) at both ends.

Images