Magnetic tunnel junction (MTJ) free layer damping reduction
In one embodiment, a system includes a sensor, the sensor having a free layer, a ferromagnetic spin sink layer spaced from the free layer, the spin sink layer being operative to reduce a spin-induced damping in the free layer during operation of the sensor, and a nonmagnetic spacer layer positioned between the free layer and the spin sink layer, the spacer layer having a long spin-diffusion length.
1. An apparatus, comprising:
an element comprising:
a free layer,
a ferromagnetic spin sink layer spaced from the free layer, the spin sink layer being operative to reduce a spin-induced damping in the free layer during operation, and
a nonmagnetic spacer layer positioned between the free layer and the spin sink layer, the spacer layer having a longer spin-diffusion length than a deposition thickness of the spacer layer.
2. The apparatus as recited in claim 1 , wherein the spacer layer is comprised of copper.
3. The apparatus as recited in claim 1 , wherein the spacer layer is comprised of a material selected from a group consisting of silver-tin alloys, silver and gold, and alloys of silver and gold.
4. The apparatus as recited in claim 1 , wherein a deposition thickness of the spacer layer is sufficient to prevent substantial magnetic coupling of the free layer and the spin sink layer.
5. The apparatus as recited in claim 1 , comprising a spin reflective layer positioned on an opposite side of the spin sink layer than the spacer layer and the free layer.
6. The apparatus as recited in claim 1 , wherein the spin sink layer has a deposition thickness in a range of about 1 nm to about 5 nm.
7. The apparatus as recited in claim 1 , wherein the spin sink layer is comprised of a material selected from a group consisting of iron, nickel, cobalt, Heusler alloys, and combinations thereof.
8. The apparatus as recited in claim 1 , comprising a nonmagnetic cap layer above the spin sink layer.
9. The apparatus as recited in claim 8 , comprising a shield above the cap layer.
10. The apparatus as recited in claim 1 , comprising a shield on the spin sink layer.
11. The apparatus as recited in claim 1 , wherein the element is a magnetic tunnel junction.
12. The apparatus as recited in claim 1 , wherein the element is a magnetoresistive sensor.
13. The apparatus as recited in claim 12 , further comprising:
a magnetic medium;
a drive mechanism for passing the magnetic medium over the sensor; and
a controller electrically coupled to the sensor for controlling operation of the sensor.
14. A magnetic random access memory device comprising the apparatus as recited in claim 1 .
15. A magnetic random access memory apparatus, comprising:
an element comprising:
a free layer,
a ferromagnetic spin sink layer spaced from the free layer, the spin sink layer being operative to reduce a spin-induced damping in the free layer during operation, and
a nonmagnetic spacer layer positioned between the free layer and the spin sink layer, the spacer layer having a long spin-diffusion length.
16. A magnetic random access memory apparatus, comprising:
an element comprising:
a free layer,
a ferromagnetic spin sink layer spaced from the free layer, the spin sink layer being operative to reduce a spin-induced damping in the free layer during operation, and
a nonmagnetic spacer layer positioned between the free layer and the spin sink layer,
wherein a deposition thickness of the spacer layer is less than a spin diffusion length of a material composition of the spacer layer.
17. The apparatus as recited in claim 16 , wherein the spacer layer is comprised of copper.
18. The apparatus as recited in claim 16 , wherein the spacer layer is comprised of a material selected from a group consisting of silver-tin alloys, silver and gold, and alloys of silver and gold.
19. The apparatus as recited in claim 16 , wherein a deposition thickness of the spacer layer is sufficient to prevent substantial magnetic coupling of the free layer and the spin sink layer.
20. The apparatus as recited in claim 16 , comprising a spin reflective layer positioned on an opposite side of the spin sink layer than the spacer layer and the free layer.
21. The apparatus as recited in claim 16 , wherein the spin sink layer has a deposition thickness in a range of about 1 nm to about 5 nm.
22. The apparatus as recited in claim 16 , wherein the spin sink layer is comprised of a material selected from a group consisting of iron, nickel, cobalt, Heusler alloys, and combinations thereof.
23. The apparatus as recited in claim 16 , comprising a nonmagnetic cap layer above the spin sink layer.
24. The apparatus as recited in claim 23 , comprising a shield above the cap layer.
25. The apparatus as recited in claim 16 , comprising a shield on the spin sink layer.
26. The apparatus as recited in claim 16 , wherein the element is a magnetic tunnel junction.
27. The apparatus as recited in claim 16 , wherein the element is a component of a memory cell.