CN105552213B - A kind of method of regulation and control magneto-resistor ratio - Google Patents

Abstract

A method for controlling the magnetoresistance ratio, comprising: 1) applying an alternating current with a fixed amplitude at both ends of a rectifying magnetoresistance device; 2) simultaneously, coupling a direct current _I on the basis of the alternating current , there is a translation of I ₁ in the output AC current signal at this time: i=I ₀ sin(wt)+I ₁ ; 3) Detect the rectified voltage V _H generated by the device as the external magnetic field changes: Wherein H represents the strength of the external magnetic field, and T represents the cycle of the alternating current; 4) adjust the size of the DC component _I1 applied to the current on the device, thereby adjusting the size of the rectified voltage V _H , and finally adjust the magnetoresistance ratio MR =(V _H -V ₀ )/V ₀ . The present invention uses the device to have both rectification magnetoresistance and DC magnetoresistance, and further realizes the adjustment of rectification voltage V _H , and finally achieves the technical effect of adjusting the ratio of magnetoresistance.

Description

A method of controlling the magnetoresistance ratio

technical field

The invention relates to a method for regulating the magnetoresistance ratio, and belongs to the technical field of magnetic sensors and magnetoelectric control.

Background technique

Generally speaking, magnetoresistance refers to the phenomenon that the resistivity changes with the change of the external magnetic field. The magnitude of the magnetoresistance is usually measured by MR=(R _H -R ₀ )/R ₀ , where R _H is the resistance under the external magnetic field H, and R ₀ is the resistance without the external magnetic field. The magnetoresistance effect has great application prospects in the fields of magnetic storage and magnetic sensors. The larger the magnetoresistance, the more sensitive the magnetic sensor made and the higher the signal-to-noise ratio. Due to the influence of the Lorentz force, all materials have a magnetoresistance effect, but generally the magnetoresistance is very small and has no practical application value. So far, anisotropic magnetoresistance, giant magnetoresistance, tunneling magnetoresistance, colossal magnetoresistance, and singular magnetoresistance have large magnetoresistance ratios, and have been successfully applied to the field of magnetic sensors or magnetic read heads.

In 2015, the spintronics research group of Shandong University successfully discovered the rectifying magnetoresistance effect in the Al/Ge Schottky junction and applied for a patent. Different from the various magnetoresistance effects mentioned above, rectified magnetoresistance refers to the phenomenon that a pure sinusoidal AC current is input and the rectified DC voltage is measured. The rectified voltage changes significantly with the magnetic field. The rectified magnetoresistance is defined as: MR=(V _H −V ₀ )/V ₀ , where V _H is the rectified voltage under the external magnetic field H, and V ₀ is the rectified voltage without the external magnetic field. The rectifying magnetoresistance effect of the Al/Ge Schottky junction at room temperature is as high as 200%, while its DC magnetoresistance is only 80%. The rectification magnetoresistance effect is the result of the synergy between the rectification effect and the magnetoresistance effect.

So far, no matter what kind of magnetoresistance mechanism is used, the magnitude of the magnetoresistance cannot be adjusted. Once the sample is prepared, the ratio of magnetoresistance is fixed, which greatly limits the application scenarios of magnetoresistance. In view of the above situation, on the basis of rectifying magnetoresistance, we achieved the goal of regulating the magnitude of magnetoresistance by adjusting the component ratio of DC current and AC current. The control method can be applied to all devices with rectifying magnetoresistance effect, and has great application prospects in the fields of magnetic sensors and magnetoelectric control.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a method for regulating the magnetoresistance ratio. The invention utilizes the joint action of alternating current and direct current to increase the magnetoresistance ratio and improve the signal-to-noise ratio and measurement precision of the magnetic sensor.

Technical scheme of the present invention is as follows:

A method for regulating the magnetoresistance ratio, comprising:

1) Apply an alternating current with a fixed amplitude to both ends of the rectifying magnetoresistance device, because the device has a rectifying magnetoresistance, so the device produces a rectifying voltage that varies with the external magnetic field;

2) At the same time, a DC current I ₁ is coupled on the basis of the AC current, and the output AC current signal at this time has a translation of I ₁ : i=I ₀ Sin(wt)+I ₁ ;

3) Detecting the rectified voltage V _H generated by the device as the external magnetic field changes: Wherein H represents the intensity of the external magnetic field, and T represents the cycle of the alternating current;

4) Adjusting the magnitude of the DC component I ₁ of the current applied to the device, thereby adjusting the magnitude of the rectified voltage V _H , and finally adjusting the magnetoresistance ratio MR=(V _H −V ₀ )/V ₀ . The present invention uses the device to have both rectification magnetoresistance and DC magnetoresistance, and then realizes the adjustment of rectification voltage V _H and finally achieves the technical effect of adjusting the ratio of magnetoresistance.

Principle of the present invention is:

On the basis of rectifying magnetoresistance, by adjusting the ratio of different DC currents and AC currents, due to the nonlinear coupling of DC magnetoresistance and AC magnetoresistance, the rectification is adjusted through the competition between DC magnetoresistance and AC magnetoresistance. The change curve of voltage with magnetic field can achieve the purpose of regulating the ratio of magnetoresistance.

Based on this method, at room temperature, we have achieved a magnetoresistance ratio of up to 2000% in silicon-based rectifier magnetoresistive devices, while its rectifier magnetoresistance is only 49.3% and DC magnetoresistance is 66.1%.

Theoretically, as long as it has rectifying magnetoresistance, it can be regulated by this method. The rectifying magnetoresistance effect can in principle be realized in a PN junction, a Schottky junction, and a magnetic tunnel junction with an asymmetric barrier, which have both a rectifying effect and a magnetoresistance effect.

The advantages of the present invention are:

1. The method for regulating the magnetoresistance ratio of the present invention can increase the magnetoresistance ratio, and improve the measurement accuracy and signal-to-noise ratio of the sensor. In silicon-based Schottky devices, the present invention achieves a magnetoresistance ratio as high as 2000% at room temperature.

2. The method for regulating the magnetoresistance ratio of the present invention is universal. It can be applied to all devices with rectifying magnetoresistance effect. For example in Schottky junctions based on silicon and germanium, in PN junctions and in magnetic tunnel junctions with asymmetrical barriers.

3. The method for regulating the magnetoresistance ratio of the present invention does not require a high working voltage (<1V), and has the advantage of low power consumption. The device will not be in a high voltage state for a long time and has a longer service life.

4. The method for regulating the magnetoresistance ratio of the present invention, the mixing of AC and DC has important application value in high-frequency signal transmission, metal electrolysis and differential conductance measurement, so the mixing of DC and AC is a very mature technology , only need to use basic components such as capacitors and resistors, and the circuit connection is simple.

5. The method for regulating the magnetoresistance ratio of the present invention is based on Schottky junctions, PN junctions, etc., compatible with today's semiconductor technology, and conducive to mass production.

Description of drawings

Fig. 1 is a schematic structural diagram of a silicon-based rectifying magnetoresistive device, wherein the direction of the current is perpendicular to the silicon substrate, and the direction of the external magnetic field is perpendicular to the direction of the current;

Figure 2 shows that at an ambient temperature of 300K, in a silicon-based Schottky junction, the amplitude of the fixed AC current is 50μA, that is, I ₀ =50μA; adjust the DC component I ₁ (-10μA～10μA) of different currents, and measure the Variation curve of voltage with magnetic field;

Fig. 3 is a diagram showing the variation of the magnetoresistance ratio with the current DC component I ₁ at an ambient temperature of 300K. A magnetoresistance ratio of up to 2000% is achieved.

detailed description:

The present invention will be described in detail below in conjunction with the embodiments and the accompanying drawings, but not limited thereto.

As shown in Figure 1-3.

Embodiment 1,

A method for regulating the magnetoresistance ratio, comprising:

1) Apply an alternating current i=I ₀ sin (wt) of a fixed amplitude to both ends of the rectifying magnetoresistance device; since the device has rectifying magnetoresistance, the device produces a rectifying voltage that varies with the external magnetic field ;

2) At the same time, a DC current I ₁ is coupled on the basis of the AC current, and the output AC current signal at this time has a translation of I ₁ : i=I ₀ sin(wt)+I ₁ ;

3) Detecting the rectified voltage V _H generated by the device as the external magnetic field changes: Wherein H represents the intensity of the external magnetic field, and T represents the cycle of the alternating current;

4) Adjusting the magnitude of the DC component I ₁ of the current applied to the device, thereby adjusting the magnitude of the rectified voltage V _H , and finally adjusting the magnetoresistance ratio MR=(V _H −V ₀ )/V ₀ . The present invention utilizes the device having both rectification magnetoresistance and DC magnetoresistance, and further realizes the adjustment of the magnitude of the rectification voltage V _H , and finally achieves the technical effect of adjusting the magnetoresistance ratio.

For the silicon-based rectifying magnetoresistance device, the method for controlling the magnetoresistance ratio as described in Embodiment 1 is used to obtain a magnetoresistance ratio of up to 2000% for the silicon-based rectifying magnetoresistance device.

Application example 1,

In the embodiment 1, the device is a silicon-based Schottky junction, and its specific processing methods include:

(1) Ultrasonic the intrinsic Si substrate with a resistivity > 1000Ω·cm and a thickness of 0.5mm with deionized water, alcohol, acetone, and alcohol for 10 minutes, and then put it into an oven to bake at 100°C, time It takes two hours; cut the intrinsic silicon into a 3mm×3mm square;

(2) put the cut square into the hydrofluoric acid with a concentration of 0.2% to remove the silicon dioxide layer of about 2nm formed by natural oxidation on the intrinsic silicon;

(3) Weld indium electrodes on the upper and lower sides of the square substrate, and form two asymmetric Schottky barrier junctions on the silicon substrate by controlling the welding time of the soldering iron, as shown in Figure 1;

(4) Use Keithley 6221 as the AC source to access both ends of the device, and use Keithley 2182 to detect the rectified voltage change at both ends. The superconducting quantum interferometer provides an external magnetic field environment, and the magnetic field is perpendicular to the direction of the current;

(5) Fix the AC amplitude of the Keithley 6221 output to 50μA, that is, I ₀ =50μA, and adjust the zero point drift (offset) of the current source, that is, superimpose a DC signal I ₁ on the AC signal, ranging from -10μA to 10μA. The curves of the rectified voltage changing with the external magnetic field are measured under different DC components I ₁ , as shown in Figure 2;

Figure 3 shows the magnetoresistance of this example under different I ₁ DC components at a temperature of 300K. It can be obtained from Fig. 3 that when I ₁ =1.53μA, the magnetoresistance ratio reaches the maximum, which is 2000%; its pure rectifying magnetoresistance, that is, when I ₁ =0, the magnetoresistance ratio is 49.3%; its DC magnetoresistance is 66.1 %. Although the DC magnetoresistance is larger than the rectified magnetoresistance, the magnetoresistance can be increased by 40 times by mixing DC and AC, which will have a wide application prospect in the field of magnetic sensors and magnetoelectric control.

Application example 2,

In said embodiment 1, said device is a germanium-based Schottky junction, and its specific processing methods include:

(1) Ultrasonicate the intrinsic Ge substrate with a resistivity of 55.6-59.4Ω cm and a thickness of 0.5mm with deionized water, alcohol, acetone, and alcohol for 10 minutes, and then put it into an oven to bake at a temperature of 100°C , the time is two hours;

(2) Put the intrinsic germanium substrate into the magnetron sputtering chamber, and sputter and grow a 100nm aluminum electrode to form an Al/Ge Schottky contact interface;

(3) Take out the germanium substrate that has grown the aluminum electrode, and cut it into a circle with a diameter of 3mm with an ultrasonic slicer;

(4) The other side of the germanium substrate is welded with an indium electrode to form an ohmic contact;

(5) Use Keithley 6221 as the AC source to access both ends of the device, and use Keithley 2182 to detect the rectified voltage change at both ends. The superconducting quantum interferometer provides an external magnetic field environment, and the magnetic field is perpendicular to the direction of the current;

(6) Fix the AC amplitude output by Keithley 6221 to 0.1mA, adjust the zero point drift (offset) of the current source, that is, superimpose a DC signal I ₁ on the AC signal, ranging from -5μA to 20μA _; Variation curve of rectified voltage with external magnetic field;

At a temperature of 300K, when I ₁ =5.228uA, the magnetoresistance ratio reaches the maximum, which is 32500%, which is much higher than its rectifying magnetoresistance (120%) and DC magnetoresistance (45%).

In short, on the basis of rectified magnetoresistance, the method of adjusting the magnetoresistance ratio by mixing the AC and DC can greatly increase the magnetoresistance ratio, which can be applied to the field of magnetic sensors to improve the measurement accuracy and signal-to-noise ratio. It provides a basis for the development of a new generation of magnetic sensors. In addition, the innovation of this invention is not only to increase the magnetoresistance ratio, but to dynamically adjust the magnitude of the magnetoresistance, so that the magnetoresistance ratio of the device can be in any range, which has great application prospects in the field of magnetoelectric control. Finally, the invention is also versatile, and can be applied to all devices with rectifying magnetoresistance, and is not limited by the principle of the device itself. For example, the invention can be used to control the magnetoresistance ratio in Schottky junctions, PN junctions and asymmetric barriers with magnetoresistance.

Claims (1)

1. A kind of 1. method of regulation and control magneto-resistor ratio, it is characterised in that this method includes：

   1) alternating current of a fixed amplitude is applied at the both ends with rectification magneto-resistance device；

   2) a DC current I simultaneously, is coupled on the basis of the alternating current₁, the ac current signal now exported deposits In I₁Translation：I=I₀sin(wt)+I₁；

   3) detect the device with external magnetic field change caused by commutating voltage V_H：Wherein H The intensity of external magnetic field is represented, T represents the cycle of the alternating current；

   4) regulation is applied to the DC component I of electric current on the device₁Size, so as to adjust commutating voltage V_HSize, finally Adjust magneto-resistor ratio MR=(V_H-V₀)/V₀。