SPIN TORQUE OSCILLATOR WITH HIGH POWER OUTPUT AND ITS APPLICATIONS

• US 20180006657A1
• Filed: 09/27/2016
• Published: 01/04/2018
• Est. Priority Date: 07/04/2016
• Status: Active Grant

• Current Assignee: Institute of Physics Chinese Academy of Sciences
• Original Assignee: Institute of Physics Chinese Academy of Sciences
• Inventors: Wei, Hongxiang, Feng, Jiafeng, Zhang, Xiaoguang, Liu, Houfang, Han, Xiufeng
• Granted Patent: US 10,135,392 B2
• Time in Patent Office: Days
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: H01F 10/193 Magnetic semiconductor compounds in general H01F1/40; multilayers, e.g. superlattices H01F10/3213
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H01F 10/329 Spin-exchange coupled multilayers wherein the magnetisation of the free layer is switched by a spin-polarised current, e.g. spin torque effect
• CPC Class Codes: H03B 15/006 using spin transfer effects or giant magnetoresistance
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

The present invention relates to a spin torque oscillator with high power output and its applications. A spin torque oscillator may include a first magnetic reference layer having a fixed magnetization, a magnetic precession layer having a magnetization capable of precessing about an initial direction, and a first barrier layer interposed between the first magnetic reference layer and the magnetic precession layer. The first barrier layer is formed of an insulating material capable of inducing a negative differential resistance for the spin torque oscillator.

Claims

1. A spin torque oscillator comprising:

a first magnetic reference layer having a fixed magnetization;

a magnetic precession layer having a magnetization capable of precessing about an initial direction; and

a first barrier layer interposed between the first magnetic reference layer and the magnetic precession layer, the first barrier layer being formed of an insulating material capable of inducing a negative differential resistance for the spin torque oscillator.

2. The spin torque oscillator of claim 1 wherein the first barrier layer is formed of a material AB having a cubic crystal structure where A represents cation sites and B represents anion sites in the cubic crystal structure, the cation sites A are occupied disorderly by at least two of Mg, Al, Zn and vacancy, and the anion sites B are occupied by one or more of O, N, Cl, F and vacancy.

3. The spin torque oscillator of claim 1 wherein the first barrier layer has a thickness in a range of 4-7 atomic layers.

4. The spin torque oscillator of claim 1 wherein the initial direction of the magnetization of the magnetic precession layer is parallel to the magnetization of the first magnetic reference layer.

5. The spin torque oscillator of claim 1 further comprising:

a second barrier layer formed of an insulating material provided on a side of the magnetic precession layer opposite to the first barrier layer; and

a second magnetic reference layer having a fixed magnetization provided on a side of the second barrier layer opposite to the magnetic precession layer.

6. The spin torque oscillator of claim 5 wherein the second barrier layer is formed of an insulating material capable of inducing a negative differential resistance.

7. The spin torque oscillator of claim 6 wherein the second barrier layer has a thickness in a range of 4-7 atomic layers.

8. The spin torque oscillator of claim 5 wherein the second magnetic reference layer has a magnetization in a direction parallel to the magnetization of the first magnetic reference layer.

9. A spin torque oscillator circuit comprising:

a first magnetic tunnel junction generating an oscillating signal under a direct current (DC) bias, the first magnetic tunnel junction comprising;

a first magnetic reference layer having a fixed magnetization;

a magnetic precession layer having a magnetization capable of precessing about an initial direction under the DC bias; and

a first barrier layer interposed between the first magnetic reference layer and the magnetic precession layer, the first barrier layer being formed of an insulating material capable of inducing a negative differential resistance under the DC bias; and

at least one amplifying circuit receiving and amplifying the oscillating signal generated by the first magnetic tunnel junction, each of the at least one amplifying circuit comprising a resistor and a second magnetic tunnel junction connected in series between a supply voltage and a ground potential, the second magnetic tunnel junction having a negative differential resistance under biasing of the supply voltage, the oscillating signal being applied to a supply voltage side of the at least one amplifying circuit, and the at least one amplifying circuit providing the amplified oscillating signal at a node between the resistor and the second magnetic tunnel junction.

10. The spin torque oscillator circuit of claim 9 wherein the second magnetic tunnel junction has a larger junction area than the first magnetic tunnel junction.

11. The spin torque oscillator circuit of claim 9 wherein the second magnetic tunnel junction itself does not generate an oscillating signal.

12. The spin torque oscillator circuit of claim 9 wherein the second magnetic tunnel junction has a multilayer structure identical to the first magnetic tunnel junction.

13. The spin torque oscillator circuit of claim 9 wherein the first barrier layer is formed of a material AB having a cubic crystal structure where A represents cation sites and B represents anion sites in the cubic crystal structure, the cation sites A are occupied disorderly by at least two of Mg, Al, Zn and vacancy, and the anion sites B are occupied by one or more of O, N, Cl, F and vacancy, and the first barrier layer has a thickness in a range of 4-7 atomic layers.

14. The spin torque oscillator circuit of claim 9 wherein the first magnetic tunnel junction further comprises:

a second barrier layer formed of an insulating material provided on a side of the magnetic precession layer opposite to the first barrier layer; and

a second magnetic reference layer having a fixed magnetization provided on a side of the second barrier layer opposite to the magnetic precession layer,

wherein the second magnetic reference layer has a magnetization in a direction parallel to the magnetization of the first magnetic reference layer.

15. The spin torque oscillator circuit of claim 9 further comprising:

a filter disposed between the first magnetic tunnel junction and the at least one amplifying circuit to filter out a DC component in the oscillating signal generated by the first magnetic tunnel junction, passing only an AC component of the oscillating signal to the at least one amplifying circuits for amplification.

16. The spin torque oscillator circuit of claim 9 wherein the at least one amplifying circuit comprise two or more amplifying circuits cascaded with each other to amplify the oscillating signal generated by the first magnetic tunnel junction.

17. The spin torque oscillator circuit of claim 16 wherein a filter is connected between adjacent ones of the two or more amplifying circuits cascaded with each other to filter out a DC component in a signal output from each amplifying circuit.

18. A method of operating a spin torque oscillator comprising a first magnetic reference layer having a fixed magnetization, a magnetic precession layer having a magnetization capable of precessing about an initial direction, and a first barrier layer interposed between the first magnetic reference layer and the magnetic precession layer, the first barrier being formed of an insulating material capable of inducing a negative differential resistance for the spin torque oscillator, the method comprising:

applying a direct current (DC) bias to the spin torque oscillator to operate it in a negative differential resistance region; and

extracting an oscillating signal output from the spin torque oscillator.

19. The method of claim 18 wherein extracting an oscillating signal output from the spin torque oscillator further comprises passing the oscillating signal output through a filter to remove a DC component contained therein.

20. The method of claim 18 wherein the DC bias applied to the spin torque oscillator is large enough to cause the magnetization of the magnetic precession layer to precess about its initial direction.