Multistate magnetic memory element using metamagnetic materials

• US 20190333559A1
• Filed: 04/13/2019
• Published: 10/31/2019
• Est. Priority Date: 04/26/2018
• Status: Active Grant

• Current Assignee: The Government Of The United States Of America, As Represented By The Secretary Of The Navy
• Original Assignee: The Government Of The United States Of America, As Represented By The Secretary Of The Navy
• Inventors: van 't Erve, Olaf M.J., Bennett, Steven P., Friedman, Adam L.
• Granted Patent: US 11,074,950 B2
• Time in Patent Office: Days
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: G11C 11/5607 using magnetic storage elements
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/85 Magnetic active materials

Abstract

A metamagnetic tunneling-based spin valve device for multistate magnetic memory comprising an electronic memory logic element with four stable resistance states. A metamagnetic tunneling-based spin valve device for multistate magnetic memory comprising a layer of a metamagnetic material, a layer of a nonmagnetic material on the layer of a metamagnetic material, and a layer of a ferromagnetic material on the layer of a nonmagnetic material. A method of making a metamagnetic tunneling-based spin valve device for multistate magnetic memory.

Claims

1. A method of making a metamagnetic tunneling-based spin valve device for multistate magnetic memory comprising the steps of:

providing a substrate;

fabricating a layer of a metamagnetic material on the substrate;

fabricating a layer of a nonmagnetic material on the layer of a metamagnetic material; and

fabricating a layer of a ferromagnetic material on the layer of a nonmagnetic material.

2. The method of making a metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 1

wherein the layer of a metamagnetic material comprises FeRh.

3. The method of making a metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 2

wherein the layer of a ferromagnetic material comprises NiFe.

4. The method of making a metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 3

wherein layer of a nonmagnetic material comprises a nonmagnetic metal.

5. The method of making a metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 4

wherein the nonmagnetic metal comprises copper.

6. The method of making a metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 1

wherein the step of fabricating a layer of a metamagnetic material on the substrate comprises the step of

sputtering or depositing by sputter deposition the layer of a metamagnetic material on the substrate.

7. The method of making a metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 6

wherein the step of sputtering or depositing by sputter deposition the layer of a metamagnetic material on the substrate comprises sputtering a layer of FeRh.

8. The method of making a metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 7

wherein the layer of FeRh is 30 nm thick.

9. The method of making a metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 8

wherein the step of sputtering or depositing by sputter deposition the layer of FeRh occurs at a temperature of 600°

C.; and

further comprising the step of

cooling the layer of FeRh to room temperature;

wherein the step of fabricating a layer of a nonmagnetic material on the layer of a metamagnetic material comprises fabricating a layer of Cu; and

wherein the step of fabricating a layer of a ferromagnetic material on the layer of a nonmagnetic material comprises fabricating a layer of NiFe.

10. A metamagnetic tunneling-based spin valve device for multistate magnetic memory comprising:

a layer of a metamagnetic material;

a layer of a nonmagnetic material on the layer of a metamagnetic material; and

a layer of a ferromagnetic material on the layer of a nonmagnetic material.

11. The metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 10 wherein the layer of a metamagnetic material comprises FeRh.

12. The metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 11 wherein the layer of a nonmagnetic material on the layer of a metamagnetic material comprises a nonmagnetic metal.

13. The metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 12 wherein the nonmagnetic metal comprises Cu.

14. The metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 13 wherein the layer of a ferromagnetic material on the layer of a nonmagnetic material comprises NiFe.

15. The metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 14 further comprising a MgO substrate or a sapphire substrate.

16. The metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim

wherein the layer of FeRh is 30 nm thick;

wherein the layer of Cu is 5 nm thick; and

wherein the layer of NiFe is 30 nm thick.

17. A metamagnetic tunneling-based spin valve device for multistate magnetic memory comprising:

an electronic memory logic element with four stable resistance states.

18. The metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 17 wherein the electronic memory logic element with four stable resistance states comprises states which depend on two physical domains.

19. The metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 18 wherein the two physical domains comprise temperature sweep direction and magnetic field.

20. The metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 17 wherein the electronic memory logic element with four stable resistance states comprises two magnetic layers and wherein the two magnetic layers are separated by a nonmagnetic layer.

21. The metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim 20

wherein one of the magnetic layers comprises FeRh;

and

wherein the nonmagnetic layer comprises a metal or a tunnel-barrier.

22. The metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim

wherein the electronic memory logic element with four stable resistance states comprises FeRh;

wherein the FeRh undergoes a magnetic phase change with temperature cycling and comprises an associated hysteresis; and

wherein the 4 stable resistance states are obtained at a fixed temperature and zero magnetic field.

23. The metamagnetic tunneling-based spin valve device for multistate magnetic memory of claim

wherein the four stable resistance states are individually addressable with temperature cycling and magnetic field cycling;

wherein the resistance depends on the relative magnetization of magnetic layers; and

wherein the metamagnetic tunneling-based spin valve device for multistate magnetic memory is used for nonvolatile electronics.