Precessional spin current structure for MRAM

• US 9,853,206 B2
• Filed: 07/30/2015
• Issued: 12/26/2017
• Est. Priority Date: 06/16/2015
• Status: Active Grant

• Current Assignee: Integrated Silicon Solution Incorporated (Uphill Investment Co.)
• Original Assignee: Spin Transfer Technologies, Inc.
• Inventors: Pinarbasi, Mustafa Michael, Tzoufras, Michail
• Primary Examiner(s): Nguyen, Duy T
• Assistant Examiner(s): Jang, Bo Bin
• Application Number:
  US14/814,036
• Publication Number:
  US 20160372656A1
• Time in Patent Office: 880 Days
• Field of Search: None
• 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 11/1675 Writing or programming circuits or methods
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/80 Constructional details
• CPC Class Codes: H10N 50/85 Magnetic active materials

Abstract

A magnetoresistive random-access memory (MRAM) is disclosed. MRAM device has a magnetic tunnel junction stack having a significantly improved performance of the free layer in the magnetic tunnel junction structure. The MRAM device utilizes a precessional spin current (PSC) magnetic layer in conjunction with a perpendicular MTJ where the in-plane magnetization direction of the PSC magnetic layer is free to rotate.

Claims

1. A magnetic device, comprising

a synthetic antiferromagnetic structure in a first plane, the synthetic antiferromagnetic structure including a magnetic reference layer, the magnetic reference layer having a magnetization vector that is perpendicular to the first plane and having a fixed magnetization direction;

a non-magnetic tunnel barrier layer in a second plane and disposed over the magnetic reference layer;

a free magnetic layer in a third plane and disposed over the non-magnetic tunnel barrier layer, the free magnetic layer having a magnetization vector that is perpendicular to the third plane and having a magnetization direction that precesses from a first magnetization direction to a second magnetization direction when a spin-polarized current passes there through, the magnetic reference layer, the non-magnetic tunnel barrier layer and the free magnetic layer forming a magnetic tunnel junction;

a non-magnetic spacer in a fourth plane and disposed over the free magnetic layer;

a precessional spin current magnetic layer in a fifth plane that is physically separated from the free magnetic layer and electronically coupled to the free magnetic layer by the non-magnetic spacer, the precessional spin current magnetic layer having a magnetization vector with a magnetization component in the fifth plane which freely rotates in any magnetic direction in the fifth plane, and

wherein the magnetization vector with the magnetization component in the fifth plane of the precessional spin current magnetic layer follows precession of the magnetization direction of the free magnetic layer, rotation of the magnetization component in the fifth plane of the precessional spin current magnetic layer causing spin polarization of electrons of electrical current passing there through to change in a manner corresponding to the magnetic vector of the precessional spin current magnetic layer, thereby creating the spin-polarized current, the spin-polarized current thereby causing spin transfer torque to assist switching of the magnetization vector of the free magnetic layer, the free magnetic layer storing a memory value.

2. The magnetic device of claim 1 wherein the precessional spin current magnetic layer has a circular shape.

3. The magnetic device of claim 1 wherein the magnetization direction of the magnetization vector of the precessional spin current magnetic layer is in the fifth plane.

4. The magnetic device of claim 1 wherein the magnetization direction of the precessional spin current magnetic layer has a magnetization component in the fifth plane that freely rotates in the fifth plane.

5. The magnetic device of claim 1 wherein the precessional spin current magnetic layer comprises CoFeB.

6. The magnetic device of claim 1 wherein the precessional spin current magnetic layer is magnetically coupled to the free magnetic layer.

7. The magnetic device of claim 1 wherein precession of the magnetization vector with the magnetization component in the fifth plane of the precessional spin current magnetic layer is synchronized to precession of the free magnetic layer.

8. The magnetic device of claim 1 wherein the magnetization vector with the magnetization component in the fifth plane of the precessional spin current magnetic layer has a rotation frequency greater than zero.

9. The magnetic device of claim 1, further comprising a current source that directs electrical current through the precessional spin current magnetic layer, the non-magnetic spacer, the free magnetic layer, the non-magnetic tunnel barrier layer, and the magnetic reference layer, wherein electrons of the electrical current are aligned in the magnetic direction of the precessional spin current magnetic layer.

10. A magnetic device, comprising:

a magnetic tunnel junction in a first plane comprising a free magnetic layer and a reference magnetic layer, the free magnetic layer and the reference magnetic layer separated by a non-magnetic tunneling barrier layer, the free magnetic layer having a magnetization vector that is perpendicular to the first plane and having a magnetization direction that precesses when a spin-polarized current passes there through from a first magnetization direction to a second magnetization direction;

a non-magnetic spacer in a second plane disposed over the free magnetic layer;

a precessional spin current magnetic layer in a third plane electronically coupled through the non-magnetic spacer to the free magnetic layer, the precessional spin current magnetic layer separated from the free magnetic layer by the non-magnetic spacer, the precessional spin current magnetic layer having a magnetization vector with a magnetization component in the third plane which freely rotates in any magnetic direction in the third plane, wherein the magnetization component in the third plane of the precessional spin current magnetic layer follows precession of the magnetization direction of the free magnetic layer upon application of a current to the device, rotation of the magnetization component in the third plane of the precessional spin current magnetic layer causing spin polarization of electrons of the current passing there through to change in a manner corresponding to the magnetic vector of the precessional spin current magnetic layer, thereby creating the spin-polarized current, the spin-polarized current thereby causing spin transfer torque to assist switching of the magnetization vector of the free magnetic layer, the free magnetic layer storing a memory value.

11. The magnetic device of claim 10 wherein the precessional spin current magnetic layer has a circular shape.

12. The magnetic device of claim 10 wherein the magnetization direction of the magnetization vector of the precessional spin current magnetic layer is in the third plane.

13. The magnetic device of claim 10 wherein the magnetization direction of the precessional spin current magnetic layer has a magnetization component in the third plane which freely rotates in the third plane.

14. The magnetic device of claim 10 wherein the precessional spin current magnetic layer comprises CoFeB.

15. The magnetic device of claim 10 wherein the precessional spin current magnetic layer is magnetically coupled to the free magnetic layer.

16. The magnetic device of claim 10 wherein precession of the magnetization vector with the magnetization component in the fifth third plane of the precessional spin current magnetic layer is synchronized to precession of the free magnetic layer.

17. The magnetic device of claim 10 wherein the magnetization vector with the magnetization component in the third plane of the precessional spin current magnetic layer has a rotation frequency greater than zero.