Method and system for providing heat assisted switching of a magnetic element utilizing spin transfer

• US 7,110,287 B2
• Filed: 02/13/2004
• Issued: 09/19/2006
• Est. Priority Date: 02/13/2004
• Status: Active Grant

• Current Assignee: Samsung Semiconductor Incorporated (Samsung Electronics Co. Ltd.)
• Original Assignee: Grandis, Inc. (Samsung Electronics Co. Ltd.)
• Inventors: Huai, Yiming, Pakala, Mahendra
• Primary Examiner(s): Elms, Richard
• Assistant Examiner(s): Wendler, Eric J.
• Application Number:
  US10/778,735
• Publication Number:
  US 20050180202A1
• Time in Patent Office: 949 Days
• Field of Search: 365/171, 365/173, 365/158, 365/87, 327/567, 257/295, 257/310, 438/3
• US Class Current: 365/171
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: G11C 11/1675 Writing or programming circuits or methods
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

A method and system for providing a magnetic element that can be used in a magnetic memory is disclosed. The magnetic element includes pinned, spacer, free, and heat assisted switching layers. The spacer layer resides between the pinned and free layers. The free layer resides between the spacer and heat assisted switching layers. The heat assisted switching layer improves thermal stability of the free layer when the free layer is not being switched, preferably via an exchange coupling. The free layer is switched using spin transfer when a write current is passed through the magnetic element. The write current preferably provides heat that reduces the heat assisted switching layer'"'"'s stabilization of the free layer. In another aspect, the magnetic element also includes second free, a second spacer, and second pinned layers. The heat assisted switching layer resides between the two free layers, which are magnetostatically coupled.

Claims

1. A magnetic element comprising:

a pinned layer;

a spacer layer, the spacer layer being nonrnagnetic;

a free layer, the spacer layer residing between the pinned layer and the free layer;

a heat assisted switching layer, the free layer residing between the spacer layer and the heat assisted switching layer, the heat assisted switching layer for improving a thermal stability of the free layer when the free layer is not being switched;

wherein the magnetic element is configured to allow the free layer to be switched due to spin transfer when a write current is passed through the magnetic element; and

wherein the heat assisted switching layer improves the thermal stability of the free layer when the free layer is not being switched via a magnetic coupling with the free layer, the magnetic coupling being substantially reduced when the write current is passed through the magnetic element.

2. The magnetic element of claim 1 wherein the heat assisted switching layer is an antiferromagnetic layer exchange coupled to the free layer, the antiferromagnetic layer being configured to have a blocking temperature that is less than or equal to a temperature of the antiferromagnetic layer when the free layer is being switched.

3. The magnetic element of claim 2 wherein the antiferromagnetic layer includes IrMn.

4. The magnetic element of claim 3 wherein the blocking temperature is not greater than two hundred degrees Celsius.

5. The magnetic element of claim 2 further comprising:

a pinning layer adjacent to the pinned layer and including an antiferromagnetic material, the pinned layer between the pinning layer and the spacer layer, the antiferromagnetic material having a second blocking temperature greater than a temperature of the magnetic element during writing.

6. The magnetic element of claim 1 wherein the spacer layer further includes a barrier layer.

7. The magnetic element of claim 1 wherein the spacer layer further includes a conductive nonmagnetic layer.

8. The magnetic element of claim 1 wherein the pinned layer further includes a first ferromagnetic layer, a second ferromagnetic layer, and a conductive nonmagnetic spacer layer between the first ferromagnetic layer and the second ferromagnetic layer, the conductive nonmagnetic spacer layer, the first ferromagnetic layer, and the second ferromagnetic layer being configured such that the first ferromagnetic layer and the second ferromagnetic layer are antiferromagnetically coupled.

9. The magnetic element of claim 1 wherein the free layer further includes a first ferromagnetic layer, a second ferromagnetic layer, and a conductive nonmagnetic spacer layer between the first ferromagnetic layer and the second ferromagnetic layer, the conductive nonmagnetic spacer layer, the first ferromagnetic layer, and the second ferromagnetic layer being configured such that the first ferromagnetic layer and the second ferromagnetic layer are antiferromagnetically coupled.

33. The magnetic element of claim 1 wherein the heat assisted switching layer substantially covers the free layer.

34. The magnetic element of claim 1 wherein the heat assisted switching layer substantially covers the first free layer.

10. A magnetic element comprising:

a first pinned layer;

a first spacer layer, the first spacer layer being nonmagnetic;

a first free layer, the first spacer layer residing between the first pinned layer and the first free layer;

a heat assisted switching layer, the first free layer residing between the first spacer layer and the heat assisted switching layer, the heat assisted switching layer for improving a thermal stability of the first free layer when the first free layer is not being switched, the heat assisted switching layer is at least two nanometers thick;

a second free layer, the heat assisted switching layer residing between the first free layer and the second free layer, the first free layer and the second free layer being magnetostatically coupled;

a second spacer layer, the second spacer layer being nonmagnetic;

a second pinned layer, the second spacer layer residing between the second free layer and the second pinned layer;

wherein the magnetic element is configured to allow the first free layer to be switched due to spin transfer when a write current is passed through the magnetic element; and

wherein the heat assisted switching layer improves the thermal stability of the first free layer when the first free layer is not being switched via a magnetic coupling with the first free layer, the magnetic coupling being substantially reduced when the write current is passed through the magnetic element.

11. The magnetic element of claim 10 wherein the first spacer layer is a conductive nonmagnetic layer.

12. The magnetic element of claim 10 wherein the first spacer layer is a barrier layer.

13. The magnetic element of claim 10 wherein the second spacer layer is a barrier layer.

14. The magnetic element of claim 10 wherein the second spacer layer is a conductive nonmagnetic layer.

15. The magnetic element of claim 10 wherein the second spacer layer is a magnetic current confined layer allowing ballistic magnetoresistance to occur between the second free layer and the second pinned layer.

16. The magnetic element of claim 10 wherein the heat assisted switching layer is an antiferromagnetic layer exchange coupled to the first free layer and the second free layer, the antiferromagnetic layer being configured to have a blocking temperature that is less than or equal to a temperature of the antiferromagnetic layer when the first free layer is being switched.

17. The magnetic element of claim 16 wherein the antiferromagnetic layer includes IrMn.

18. The magnetic element of claim 17 wherein the blocking temperature is not greater than two hundred degrees Celsius.

19. The magnetic element of claim 16 further comprising:

a first pinning layer adjacent to the first pinned layer and including an antiferromagnetic material, the first pinned layer between the first pinning layer and the first spacer layer, the antiferromagnetic material having a second blocking temperature greater than a temperature of magnetic element during writing.

20. The magnetic element of claim 16 further comprising:

a second pinning layer adjacent to the second pinned layer and including an antiferromagnetic material, the second pinned layer between the second pinning layer and the second spacer layer, the antiferromagnetic material having a second blocking temperature greater than a temperature of the magnetic element during writing.

21. The magnetic element of claim 10 wherein the first pinned layer further includes a first ferromagnetic layer, a second ferromagnetic layer, and a conductive nonmagnetic spacer layer between the first ferromagnetic layer and the second ferromagnetic layer.

22. The magnetic element of claim 21 wherein the second pinned layer further includes a third ferromagnetic layer, a fourth ferromagnetic layer having a first magnetization, and a second conductive nonmagnetic spacer layer residing between the third ferromagnetic layer and the fourth ferromagnetic layer, the second ferromagnetic layer being adjacent to the first spacer layer, the third ferromagnetic layer being adjacent to the second spacer layer, the first ferromagnetic layer having a first magnetization, the second ferromagnetic layer having a second magnetization parallel to the first magnetization.

23. The magnetic element of claim 10 wherein the first free layer further includes a first ferromagnetic layer, a second ferromagnetic layer, and a conductive nonmagnetic spacer layer between the first ferromagnetic layer and the second ferromagnetic layer.

24. The magnetic element of claim 10 wherein the second pinned layer further includes a first ferromagnetic layer, a second ferromagnetic layer, and a conductive nonmagnetic spacer layer between the first ferromagnetic layer and the second ferromagnetic layer.

25. The magnetic element of claim 10 wherein the second free layer further includes a first ferromagnetic layer, a second ferromagnetic layer, and a conductive nonmagnetic spacer layer between the first ferromagnetic layer and the second ferromagnetic layer.

26. A method of providing magnetic element comprising:

(a) providing a pinned layer;

(b) providing a spacer layer, the spacer layer being nonmagnetic;

(c) providing a free layer, the spacer layer residing between the pinned layer and the free layer;

(d) providing a heat assisted switching layer, the free layer residing between the spacer layer and the heat assisted switching layer, the heat assisted switching layer for improving a thermal stability of the free layer when the free layer is not being switched, and the heat assisted switching layer improving the thermal stability of the free layer when the free layer is not being switched via a magnetic coupling with the free layer, the magnetic coupling being substantially reduced when the write current is passed through the magnetic element;

wherein the magnetic element is configured to allow the free layer to be switched due to spin transfer when a write current is passed through the magnetic element; and

wherein the heat assisted switching layer improves the thermal stability of the free layer when the free layer is not being switched via a magnetic coupling with the free layer, the magnetic coupling being substantially reduced when the write current is passed through the magnetic element.

27. The method of claim 26 wherein the heat assisted switching layer is an antiferromagnetic layer exchange coupled to the free layer, the antiferromagnetic layer being configured to have a blocking temperature that is less than or equal to a temperature of the antiferromagnetic layer when the free layer is being switched.

28. The method of claim 27 wherein the antiferromagnetic layer includes IrMn.

29. The method claim of 28 wherein the blocking temperature is not greater than two hundred degrees Celsius.

30. A method for providing magnetic element comprising:

(a) providing a first pinned layer;

(b) providing a first spacer layer, the first spacer layer being nonmagnetic;

(c) providing a first free layer, the first spacer layer residing between the first pinned layer and the first free layer;

(d) providing a heat assisted switching layer, the first free layer residing between the first spacer layer and the heat assisted switching layer, the heat assisted switching layer for improving a thermal stability of the first free layer when the first free layer is not being switched;

(e) providing a second free layer, the heat assisted switching layer residing between the first free layer and the second free layer, the first free layer and the second free layer being magnetostatically coupled;

(f) providing a second spacer layer, the second spacer layer being nonmagnetic;

(g) providing a second pinned layer, the second spacer layer residing between the second free layer and the second pinned layer;

wherein the magnetic element is configured to allow the first free layer to be switched due to spin transfer when a write current is passed through the magnetic element; and

wherein the heat assisted switching layer improves the thermal stability of the first free layer when the first free layer is not being switched via a magnetic coupling with the first free layer, the magnetic coupling being substantially reduced when the write current is passed through the magnetic element.

31. A method for utilizing a magnetic element in a magnetic memory comprising:

heating a portion of the magnetic element during switching of the magnetic element, the magnetic element including a pinned layer, a spacer layer, a free layer, and a heat assisted switching layer, the free layer residing between the spacer layer and the heat assisted switching layer, the heat assisted switching layer for improving a thermal stability of the free layer when the free layer is not being switched, the spacer layer being nonmagnetic and layer residing between the pinned layer and the free layer, the portion being heated including the heat assisted switching layer; and

applying a read current for reading the magnetic element;

wherein the magnetic element is configured to allow the free layer to be switched due to spin transfer when a write current is passed through the magnetic element.

32. The method of claim 31 wherein the heating step includes the step of:

applying a write current to the magnetic element, the write current being used to heat the portion of the magnetic element.

35. The method of claim 31 wherein the heat assisted switching layer improves the thermal stability of the free layer when the free layer is not being switched via a magnetic coupling with the free layer, the magnetic coupling being substantially reduced when the magnetic element is heated.