IP Library › Granted Patent US 8,203,192
Granted Patent B2
US 8,203,192 · App. 13/086,613 · Granted Jun 19, 2012

STRAM with compensation element and method of making the same

View Patent ↗
Loading inventors, assignments & file history…
Monitor This Case
Get email alerts when status or documents change.
Order Certified Copies
Most orders are placed with the USPTO same day — all within 24 business hours.
Order via The Patent Place →
Pre-filled with this patent's details
Quick Facts
Patent No.
US 8,203,192
App. No.
13/086,613
Granted
Jun 19, 2012
Kind
B2
Abstract

Spin-transfer torque memory having a compensation element is disclosed. A spin-transfer torque memory unit includes a free magnetic layer having a magnetic easy axis and a magnetization orientation that can change direction due to spin-torque transfer when a write current passes through the spin-transfer torque memory unit; a reference magnetic element having a magnetization orientation that is pinned in a reference direction; an electrically insulating and non-magnetic tunneling barrier layer separating the free magnetic layer from the magnetic reference element; and a compensation element adjacent to the free magnetic layer. The compensation element applies a bias field on the magnetization orientation of the free magnetic layer. The bias field is formed of a first vector component parallel to the easy axis of the free magnetic layer and a second vector component orthogonal to the easy axis of the free magnetic layer. The bias field reduces a write current magnitude required to switch the direction of the magnetization orientation of the free magnetic layer.

Claims (33)

1. A spin-transfer torque memory unit, comprising:

a free magnetic layer having a magnetic easy axis and a magnetization orientation that can change direction due to spin-torque transfer when a write current passes through the spin-transfer torque memory unit;

a reference magnetic element having a magnetization orientation that is pinned in a reference direction;

an electrically insulating and non-magnetic tunneling barrier layer separating the free magnetic layer from the magnetic reference element; and

a compensation element adjacent to the free magnetic layer, the compensation element applying a bias field on the magnetization orientation of the free magnetic layer, the bias field comprising a first vector component parallel to the easy axis of the free magnetic layer and a second vector component orthogonal to the easy axis of the free magnetic layer, wherein the bias field reduces a write current magnitude required to switch the direction of the magnetization orientation of the free magnetic layer.

2. A spin-transfer torque memory unit according to claim 1 , further comprising an electrically conductive and non-magnetic spacer layer separating the compensation element from the free magnetic layer.

3. A spin-transfer torque memory unit according to claim 1 , further comprising a second electrically insulating and non-magnetic spacer layer separating the compensation element from the free magnetic layer.

4. A spin-transfer torque memory unit according to claim 1 , wherein the reference magnetic element comprises a synthetic antiferromagnetic reference element.

5. A spin-transfer torque memory unit according to claim 1 , wherein the compensation element comprises a ferromagnetic material having a hard magnetic property.

6. A spin-transfer torque memory unit according to claim 2 , wherein the electrically conductive and non-magnetic spacer layer has a thickness in a range from 1 to 10 nanometers.

7. A spin-transfer torque memory unit according to claim 1 , wherein the compensation element and the free magnetic layer have a similar shape.

8. A spin-transfer torque memory unit according to claim 1 , wherein the compensation element applies a bias field on the magnetization orientation of the free magnetic layer and the bias field is configured to be set after a magnetic property of the spin-transfer torque memory unit is measured.

9. A spin-transfer torque memory apparatus, comprising:

a spin-transfer torque memory unit comprising:

a free magnetic layer having a magnetic easy axis and a magnetization orientation that can change direction due to spin-torque transfer when a write current passes through the spin-transfer torque memory unit;

a reference magnetic element having a magnetization orientation that is pinned in a reference direction; and

an electrically insulating and non-magnetic tunneling barrier layer separating the free magnetic layer from the magnetic reference element; and

a compensation element adjacent to the spin-transfer torque memory unit, the compensation element applying a bias field on the magnetization orientation of the free magnetic layer, wherein the bias field is configured to be set after a magnetic property of the spin-transfer torque memory unit is measured.

10. A spin-transfer torque memory apparatus according to claim 9 , wherein an electrically conductive and non-magnetic spacer layer separates the compensation element from the free magnetic layer.

11. A spin-transfer torque memory apparatus according to claim 9 , further comprising an magnetic field generating element that applies a magnetic field to the compensation element and sets the bias field.

12. A spin-transfer torque memory apparatus according to claim 9 , wherein the compensation element comprises a ferromagnetic material having a hard magnetic property.

13. A spin-transfer torque memory apparatus according to claim 9 , wherein the electrically conductive and non-magnetic spacer layer has a thickness in a range from 1 to 10 nanometers.

14. A spin-transfer torque memory apparatus according to claim 9 , wherein the compensation element and the free magnetic layer have a similar shape.

15. An article, comprising:

a free magnetic layer having a magnetic easy axis and a magnetization orientation that can change direction due to spin-torque transfer when a current passes through the spin-transfer torque memory unit;

a reference magnetic element having a magnetization orientation that is pinned in a reference direction;

an electrically insulating and non-magnetic tunneling barrier layer separating the free magnetic layer from the magnetic reference element; and

a compensation element adjacent to the free magnetic layer, the compensation element applying a bias field on the magnetization orientation of the free magnetic layer, the bias field comprising a first vector component parallel to the easy axis of the free magnetic layer and a second vector component orthogonal to the easy axis of the free magnetic layer, wherein the bias field reduces a current magnitude required to switch the direction of the magnetization orientation of the free magnetic layer.

16. An article according to claim 15 , further comprising an electrically conductive and non-magnetic spacer layer separating the compensation element from the free magnetic layer.

17. An article according to claim 15 , further comprising a second electrically insulating and non-magnetic spacer layer separating the compensation element from the free magnetic layer.

18. An article according to claim 15 , wherein the reference magnetic element comprises a synthetic antiferromagnetic reference element.

19. An article according to claim 15 , wherein the compensation element comprises a ferromagnetic material having a hard magnetic property.

20. An article according to claim 15 , wherein the compensation element applies a bias field on the magnetization orientation of the free magnetic layer and the bias field is configured to be set after a magnetic property of the spin-transfer torque memory unit is measured.