Apparatus and methods for magnetic memory devices with magnetic assist layer

Patent metadata

Field	Value
Publication number	US-11283008-B1
Application number	US-202117172190-A
Country	US
Kind code	B1
Filing date	Feb 10, 2021
Priority date	Aug 31, 2020
Publication date	Mar 22, 2022
Grant date	Mar 22, 2022

Abstract

An apparatus is provided that includes a magnetic tunnel junction, a magnetic assist layer coupled to the magnetic tunnel junction, a non-magnetic layer disposed between the free layer and the magnetic assist layer, and a spin Hall effect layer coupled to the magnetic assist layer. The magnetic tunnel junction includes a free layer in a plane, the free layer including a switchable magnetization direction perpendicular to the plane. The magnetic assist layer includes a magnetization direction parallel to the plane and free to rotate about an axis perpendicular to the plane.

First claim

The invention claimed is:

1. An apparatus comprising:
a magnetic tunnel junction that includes a free layer in a plane, the free layer comprising a switchable magnetization direction perpendicular to the plane;
a magnetic assist layer coupled to the magnetic tunnel junction, the magnetic assist layer comprising a magnetization direction parallel to the plane and free to rotate about an axis perpendicular to the plane;
a non-magnetic layer disposed between the free layer and the magnetic assist layer; and
a spin Hall effect layer coupled to the magnetic assist layer.

2. The apparatus of claim 1 , wherein the spin Hall effect layer is configured to selectively control oscillation of the magnetization direction of the magnetic assist layer.

3. The apparatus of claim 1 , wherein in response to a first voltage pulse applied across the spin Hall effect layer, a spin orbit torque is applied to the magnetic assist layer causing the magnetization direction of the magnetic assist layer to oscillate around an axis normal to the plane.

4. The apparatus of claim 3 , wherein in response to a second voltage pulse applied across the magnetic tunnel junction and the magnetic assist layer, a spin transfer torque is applied to the free layer causing the magnetization direction of the free layer to begin precessing.

5. The apparatus of claim 4 , further comprising circuitry configured to apply the second voltage pulse across the magnetic tunnel junction and the magnetic assist layer at a same starting time as a starting time when the first voltage pulse is applied across the spin Hall effect layer.

6. The apparatus of claim 4 , further comprising circuitry configured to apply the second voltage pulse across the magnetic tunnel junction and the magnetic assist layer at a starting time after a starting time when the first voltage pulse is applied across the spin Hall effect layer.

7. The apparatus of claim 4 , further comprising circuitry configured to control the timing of the first and second voltage pulses so that the first voltage pulse is terminated before the second voltage pulse.

8. The apparatus of claim 1 , wherein in response to a first voltage pulse applied across the spin Hall effect layer, the magnetization direction of the magnetic assist layer oscillates around an axis normal to the plane.

9. The apparatus of claim 8 , wherein in response to a second voltage pulse applied across the magnetic tunnel junction and the magnetic assist layer, the magnetization direction of the free layer begins precessing.

10. The apparatus of claim 1 , further comprising a first terminal coupled to a first end of the spin Hall effect layer, a second terminal coupled to a second end of the spin Hall effect layer, and a third terminal coupled to the magnetic tunnel junction.

11. A method comprising:
applying for a first time interval a first voltage pulse across a first terminal and a second terminal of a spin Hall effect layer that is coupled to a stack comprising a magnetic assist layer, a non-magnetic layer and a magnetic tunnel junction that includes a free layer in a plane, the free layer comprising a switchable magnetization direction perpendicular to the plane, the magnetic assist layer comprising a magnetization direction parallel to the plane and free to rotate about an axis perpendicular to the plane;
applying for a second time interval a second voltage pulse across the second terminal and a third terminal coupled to the magnetic tunnel junction, the second time interval longer than the first time interval, and the first time interval overlapping a portion of the second time interval; and
switching the magnetization direction of the free layer.

12. The method of claim 11 , wherein the second time interval starts at a same time as the first time interval.

13. The method of claim 11 , wherein the second time interval starts after the first time interval.

14. The method of claim 11 , further comprising turning OFF the first voltage pulse before turning OFF the second voltage pulse.

15. The method of claim 11 , further comprising selectively controlling oscillation of the magnetization direction of the magnetic assist layer.

16. The method of claim 11 , wherein in response to the first voltage pulse, the magnetization direction of the magnetic assist layer oscillates around an axis normal to the plane.

17. The method of claim 11 , wherein in response to the second voltage pulse, the magnetization direction of the free layer begins precessing.

18. The method of claim 11 , wherein the spin Hall effect layer comprises any of a heavy metal and a topological insulator.

19. An MRAM non-volatile memory cell comprising:
a spin Hall effect layer;
a magnetic tunnel junction that includes a free layer in a plane, the free layer comprising a switchable magnetization direction perpendicular to the plane; and
a magnetic assist layer disposed between the spin Hall effect layer and the magnetic tunnel junction, the magnetic assist layer comprising a magnetization direction parallel to the plane and free to rotate about an axis perpendicular to the plane,
wherein the spin Hall effect layer is configured to turn ON and turn OFF torque provided by the magnetic assist layer to assist switching the magnetization direction of the free layer.

20. The MRAM non-volatile memory cell of claim 19 , wherein to turn ON the torque:
a first voltage pulse is applied across the spin Hall effect layer to generate a spin orbit torque to cause the magnetization direction of the magnetic assist layer to oscillate, and
a second voltage pulse across is applied across the magnetic tunnel junction and the magnetic assist layer to generate a spin transfer torque to cause the magnetization direction of the free layer to deterministically switch.

Assignees

• Western Digital Tech Inc

Inventors

• Nguyen Thao A
• Ho Michael
• Bai Zhigang
• Liu Xiaoyong
• Li Zhanjie
• Ahn Yongchul
• Jiang Hongquan
• Le Quang

Classifications

• G11C11/1693

  Timing circuits or methods · CPC title

• G11C11/1675

  Writing or programming circuits or methods · CPC title

• G11C11/161 Primary

  details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell · CPC title

• G11C11/18

  using Hall-effect devices · CPC title

• G11C11/1659

  Cell access · CPC title