Templating layers for perpendicularly magnetized heusler films

Patent metadata

Field	Value
Publication number	US-10177305-B2
Application number	US-201715410594-A
Country	US
Kind code	B2
Filing date	Jan 19, 2017
Priority date	Jan 19, 2017
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

Devices are described that include a multi-layered structure that is non-magnetic at room temperature, and which comprises alternating layers of Co and at least one other element E (such as Ga, Ge, and Sn). The composition of this structure is represented by Co1-xEx, with x being in the range from 0.45 to 0.55. The structure is in contact with a first magnetic layer that includes a Heusler compound. An MRAM element may be formed by overlying, in turn, the first magnetic layer with a tunnel barrier, and the tunnel barrier with a second magnetic layer (whose magnetic moment is switchable). Improved performance of the MRAM element may be obtained by placing a pinning layer between the first magnetic layer and the tunnel barrier.

First claim

The invention claimed is:

1. A device, comprising:
a multi-layered structure that is non-magnetic at room temperature, the structure comprising alternating layers of Co and at least one other element E selected from the group consisting of Ga, Ge, and Sn, wherein the composition of the structure is represented by Co 1-x E x , with x being in the range from 0.45 to 0.55; and
a first magnetic layer that includes a Heusler compound, the magnetic layer being in contact with the structure.

2. The device of claim 1 , wherein the magnetic moment of the magnetic layer is substantially perpendicular to the interface between the structure and the magnetic layer.

3. The device of claim 2 , wherein the magnetic layer has a thickness of less than 5 nm.

4. The device of claim 2 , wherein the magnetic layer has a thickness of less than 3 nm.

5. The device of claim 2 , wherein the magnetic layer has a thickness of one unit cell.

6. The device of claim 1 , wherein the Heusler compound is selected from the group consisting of Mn 3.1-z Ge, Mn 3.1-z Sn, and Mn 3.1-z Sb, with z being in the range from 0 to 1.1.

7. The device of claim 1 , wherein the Heusler compound is a ternary Heusler.

8. The device of claim 7 , wherein the ternary Heusler is Mn 3.1-z Co 1.1-y Sn, wherein z≤1.2 and y≤1.0.

9. The device of claim 1 , wherein E is Ga.

10. The device of claim 1 , wherein E is Ge.

11. The device of claim 1 , wherein E is Sn.

12. The device of claim 1 , comprising a substrate underlying the multi-layered structure.

13. The device of claim 12 , comprising a tunnel barrier overlying the first magnetic layer, thereby permitting current to pass through both the tunnel barrier and the first magnetic layer.

14. The device of claim 13 , comprising a second magnetic layer in contact with the tunnel barrier.

15. The device of claim 14 , wherein the tunnel barrier is MgO.

16. A device, comprising:
a substrate;
a multi-layered structure that is non-magnetic at room temperature, the structure comprising alternating layers of Co and at least one other element E selected from the group consisting of Ga, Ge, and Sn, wherein the composition of the structure is represented by Co 1-x E x , with x being in the range from 0.45 to 0.55, wherein the structure overlies the substrate;
a first magnetic layer that includes a Heusler compound, the magnetic layer being in contact with the structure;
a tunnel barrier overlying the first magnetic layer; and
a second magnetic layer in contact with the tunnel barrier, wherein the second magnetic layer has a magnetic moment that is switchable.

17. The device of claim 16 , comprising a capping layer in contact with the second magnetic layer.

18. The device of claim 16 , wherein the first magnetic layer includes Mn and an element selected from the group consisting of Sn, Sb, and Ge.

19. The device of claim 18 , wherein the first magnetic layer further includes Co.

20. A method, comprising:
using the device of claim 14 as a memory element.

21. A method, comprising:
using the device of claim 12 as part of a racetrack memory device.

22. A method of forming the device of claim 1 , comprising:
depositing Co and Ge, thereby forming a composite layer on a substrate;
annealing the composite layer, so that at least one layer of Co and at least one layer of Ge are formed from the composite layer, thereby forming the multi-layered structure; and
depositing the magnetic layer over the multi-layered structure.

23. The method of claim 22 , wherein the annealing takes place at a temperature of at least 400° C., and the element E includes Ga.

24. The method of claim 22 , wherein the annealing takes place at a temperature of at least 400° C., and the element E includes Ge.

25. The method of claim 22 , wherein the annealing takes place at a temperature less than 400° C., and the element E includes Sn.

26. The method of claim 22 , wherein the substrate is MgO.

27. The method of claim 26 , wherein a layer of Cr overlies the MgO.

Assignees

• IBM

Inventors

• Jeong Jaewoo
• Parkin Stuart S P
• Samant Mahesh G

Classifications

• C22F1/10

  of nickel or cobalt or alloys based thereon · CPC title

• H01L43/08

  Electricity · mapped topic

• H01F10/30

  characterised by the composition of the intermediate layers {, e.g. seed, buffer, template, diffusion preventing, cap layers (H01F10/06 and H01F10/32 take precedence)} · CPC title

• H01L43/10 Primary

  Electricity · mapped topic

• H01F10/3254

  the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ] · CPC title