Hybrid write mechanism for high speed and high density magnetic random access memory

• US 7,006,375 B2
• Filed: 06/06/2003
• Issued: 02/28/2006
• Est. Priority Date: 06/06/2003
• Status: Expired due to Fees

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Covington, Mark William
• Primary Examiner(s): Phung, Anh
• Assistant Examiner(s): NGUYEN, HIEN N
• Application Number:
  US10/456,451
• Publication Number:
  US 20040246775A1
• Time in Patent Office: 998 Days
• Field of Search: 365/173, 365/158, 365/171
• US Class Current: 365/173
• CPC Class Codes: G11C 11/15 using multiple magnetic layers G11C11/155 takes precedence

Abstract

A method of writing to a magnetic random access memory comprising: producing a magnetic field along a magnetically hard axis of a free layer of a magnetoresistive element; and passing current through the magnetoresistive element to change a direction of magnetization of the free layer by spin momentum transfer. A magnetic random access memory that operates in accordance with the method is also included.

Claims

1. A method of writing to a magnetic random access memory comprising:

producing a magnetic field along a magnetically hard axis of a free layer of a magnetoresistive element; and

passing current through the magnetoresistive element to change a direction of magnetization of the free layer by spin momentum transfer.

2. The method of claim 1, wherein the step of producing a magnetic field along a magnetically hard axis of a free layer of a magnetoresistive element comprises:

passing a current through a first conductor located adjacent to the magnetoresistive element.

3. The method of claim 1, further comprising:

passing a current through a second conductor located adjacent to the magnetoresistive element, wherein the first and second conductors are not parallel with each other.

4. The method of claim 1, wherein the step of passing current through the magnetoresistive element to change a direction of magnetization of the free layer by spin momentum transfer comprises:

passing current through a first conductor connected to a first end of the magnetoresistive element; and

passing current through a second conductor connected to a second end of the magnetoresistive element;

wherein the first conductor serves as the means for producing a magnetic field along a magnetically hard axis of a free layer of a magnetoresistive element.

5. The method of claim 1, wherein the step of producing a magnetic field along a magnetically hard axis of a free layer of a magnetoresistive element comprises:

passing current through a first conductor having a first portion positioned adjacent to a first end of the magnetoresistive element and a second portion connected to a second end of the magnetoresistive element.

6. The method of claim 1, wherein the step of producing a magnetic field along a magnetically hard axis of a free layer of a magnetoresistive element causes the magnetization of the free layer to precess around an equilibrium direction;

and

the current through the magnetoresistive element is applied at times when the magnetization of the free layer overshoots the equilibrium direction.

7. The method of claim 1, wherein the magnetoresistive element comprises:

a pinned layer; and

a nonmagnetic layer positioned between the free layer and the pinned layer.

8. The method of claim 7, wherein the magnetoresistive element further comprises:

a nano-oxide layer in either the free layer, the pinned layer, or both the free layer and a pinned layer.

9. The method of claim 1, wherein the magnetoresistive element comprises:

a first pinned layer;

a first nonmagnetic insulating tunnel barrier layer positioned between the free layer and the pinned layer;

a second pinned layer; and

a second nonmagnetic layer positioned between the free layer and the pinned layer.

10. A magnetic random access memory comprising:

means for producing a magnetic field along a magnetically hard axis of a free layer of a magnetoresistive element; and

means for passing current through the magnetoresistive element to change a direction of magnetization of the free layer by spin momentum transfer.

11. The magnetic random access memory of claim 10, wherein the means for producing a magnetic field along a magnetically hard axis of a free layer of a magnetoresistive element comprises:

a first conductor positioned adjacent to the magnetoresistive element.

12. The magnetic random access memory of claim 11, further comprising:

a second conductor positioned adjacent to the magnetoresistive element, wherein the first and second conductors are not parallel with each other.

13. The magnetic random access memory of claim 10, wherein means for passing current through the magnetoresistive element to change a direction of magnetization of the free layer by spin momentum transfer comprises:

a first conductor connected to a first end of the magnetoresistive element; and

a second conductor connected to a second end of the magnetoresistive element;

wherein the first conductor serves as the means for producing a magnetic field along a magnetically hard axis of a free layer of a magnetoresistive element.

14. The magnetic random access memory of claim 10, wherein the means for producing a magnetic field along a magnetically hard axis of a free layer of a magnetoresistive element comprises:

a first conductor having a first portion positioned adjacent to a first end of the magnetoresistive element and a second portion connected to a second end of the magnetoresistive element.

15. The magnetic random access memory of claim 10, wherein the magnetoresistive element comprises:

a pinned layer; and

a nonmagnetic layer positioned between the free layer and the pinned layer.

16. The magnetic random access memory of claim 15, wherein the pinned layer comprises one of:

a single layer of soft ferromagnetic material exchange biased by an antiferromagnet;

a synthetic antiferromagnet pinned by exchange coupling to an antiferromagnet or permanent magnet;

a single permanent magnet layer;

or a soft ferromagnet exchange coupled to a permanent magnet.

17. The magnetic random access memory of claim 15, further comprising:

a nano-oxide layer in either the free layer, the pinned layer, or both the free layer and a pinned layer.

18. The magnetic random access memory of claim 10, wherein the magnetoresistive element comprises:

a first pinned layer;

a first nonmagnetic layer positioned between the free layer and the pinned layer;

a second pinned layer; and

a second nonmagnetic layer positioned between the free layer and the pinned layer.

19. The magnetic random access memory of claim 10, further comprising;

means for connecting the magnetoresistive element to a current source.

20. The magnetic random access memory of claim 11, wherein the first conductor includes a tapered region.