Spin-transfer switching magnetic element utilizing a composite free layer comprising a superparamagnetic layer

1. A magnetic tunnel junction (MTJ) storage element comprising:

a stack comprising a pinned layer and a barrier layer; and

a composite free layer formed on the barrier layer, comprising a first free layer, a nonmagnetic spacer layer and a superparamagnetic layer, such that the spacer layer is interspersed between the first free layer and the superparamagnetic layer.

2. The MTJ storage element of claim 1 , further comprising an interlayer exchange coupling between the first free layer and the superparamagnetic layer.

3. The MTJ storage element of claim 2 , wherein a magnetic polarization of the first free layer is aligned parallel to a magnetic polarization of the superparamagnetic layer.

4. The MTJ storage element of claim 2 , wherein a magnetic polarization of the first free layer is aligned anti-parallel to a magnetic polarization of the superparamagnetic layer.

5. The MTJ storage element of claim 1 , further comprising an interlayer fringe coupling between the first free layer and the superparamagnetic layer.

6. The MTJ storage element of claim 5 , wherein a magnetic polarization of the first free layer is aligned anti-parallel to a magnetic polarization of the superparamagnetic layer.

7. The MTJ storage element of claim 1 , wherein the superparamagnetic layer is formed from a ferromagnetic layer of reduced thickness.

8. The MTJ storage element of claim 1 , wherein the superparamagnetic layer is formed from an antiferromagnetic layer of reduced thickness.

9. The MTJ storage element of claim 1 , wherein the superparamagnetic layer is formed from a nonmagnetic material doped with ferromagnetic elements.

10. The MTJ storage element of claim 1 , wherein the superparamagnetic layer is formed from a ferromagnetic material doped with nonmagnetic elements.

11. The MTJ storage element of claim 1 , wherein the superparamagnetic layer is formed from a laminated structure comprising one or more layers of ferromagnetic elements, interspersed with one or more layers of nonmagnetic elements.

12. The MTJ storage element of claim 1 , further comprising an antiferromagnetic material in contact with the pinned layer, formed below the pinned layer.

13. The MTJ storage element of claim 1 , wherein the pinned layer is a pinned layer stack comprising two or more layers.

14. The MTJ storage element according to claim 1 , wherein the storage element is applied in an electronic device, selected from the group consisting of a set top box, music player, video player, entertainment unit, navigation device, communications device, personal digital assistant (PDA), fixed location data unit, and a computer, into which the MTJ storage element is integrated.

15. The MTJ storage element according to claim 1 , wherein the storage element is integrated in a Spin Transfer Torque Magnetoresistive Random Access Memory (STT-MRAM).

16. The STT-MRAM device according to claim 15 , wherein the STT-MRAM device is integrated in at least one semiconductor die.

17. A method of forming a magnetic tunnel junction (MTJ) storage element, the method comprising:

forming a stack comprising a pinned layer and a barrier layer; and

forming a composite free layer on top of the barrier layer comprising a first free layer, a nonmagnetic spacer layer and a superparamagnetic layer, such that the spacer layer is interspersed between the first free layer and the superparamagnetic layer.

18. The method of claim 17 , further comprising coupling the first free layer and the superparamagnetic layer via interlayer exchange coupling.

19. The method of claim 18 , wherein a magnetic polarization of the first free layer is aligned parallel to a magnetic polarization of the superparamagnetic layer.

20. The method of claim 18 , wherein a magnetic polarization of the first free layer is aligned anti-parallel to a magnetic polarization of the superparamagnetic layer.

21. The method of claim 17 , further comprising:

coupling the first free layer the superparamagnetic layer via interlayer fringe coupling.

22. The method of claim 21 , wherein a magnetic polarization of the first free layer is aligned anti-parallel to a magnetic polarization of the superparamagnetic layer.

23. The method of claim 17 , wherein the superparamagnetic layer is formed by reducing the thickness of a ferromagnetic or antiferromagnetic layer.

24. The method of claim 17 , wherein the superparamagnetic layer is formed by doping a nonmagnetic material with ferromagnetic elements.

25. The method of claim 17 , wherein the superparamagnetic layer is formed by doping a ferromagnetic material with nonmagnetic elements.

26. The method of claim 17 , wherein the superparamagnetic layer is formed by interspersing one or more layers of nonmagnetic elements with one or more layers of ferromagnetic elements.

27. The method according to claim 17 , wherein the MTJ storage element is applied in an electronic device, selected from the group consisting of a set top box, music player, video player, entertainment unit, navigation device, communications device, personal digital assistant (PDA), fixed location data unit, and a computer, into which the MTJ storage element is integrated.

28. The method according to claim 17 , wherein the MTJ storage element is integrated in a Spin Transfer Torque Magnetoresistive Random Access Memory (STT-MRAM).

29. A magnetic tunnel junction (MTJ) storage element comprising:

a first magnetic means for holding a first polarization;

a composite magnetic means for holding a second polarization comprising

ferromagnetic means;

superparamagnetic means; and

nonmagnetic means interspersed between the ferromagnetic means and the superparamagnetic means, wherein a thickness of the nonmagnetic means controls a manner of coupling between the ferromagnetic means and the superparamagnetic means; and

insulating means interspersed between the first magnetic means and composite magnetic means to enable a flow of tunneling current between the first magnetic means and the composite magnetic means.

30. The MTJ storage element of claim 29 , wherein the manner of coupling between the ferromagnetic means and the superparamagnetic means is interlayer exchange coupling.

31. The MTJ storage element of claim 30 , wherein a magnetic polarization of the ferromagnetic means is aligned parallel to a magnetic polarization of the superparamagnetic means.

32. The MTJ storage element of claim 30 , wherein a magnetic polarization of the ferromagnetic means is aligned anti-parallel to a magnetic polarization of the superparamagnetic means.

33. The MTJ storage element of claim 29 , wherein the manner of coupling between the ferromagnetic means and the superparamagnetic means is interlayer fringe coupling.

34. The MTJ storage element of claim 33 , wherein a magnetic polarization of the ferromagnetic means is aligned anti-parallel to a magnetic polarization of the superparamagnetic means.

35. The MTJ storage element of claim 29 , wherein the superparamagnetic means is formed from a ferromagnetic or anti-ferromagnetic material of reduced thickness.

36. The MTJ storage element of claim 29 , wherein the superparamagnetic means is formed from a nonmagnetic material doped with ferromagnetic elements.

37. The MTJ storage element of claim 29 , wherein the superparamagnetic means is formed from a ferromagnetic material doped with nonmagnetic elements.

38. The MTJ storage element of claim 29 , wherein the superparamagnetic means is formed from a laminated structure comprising one or more layers of ferromagnetic elements, interspersed with one or more layers of nonmagnetic elements.

39. The MTJ storage element according to claim 29 , wherein the MTJ storage element is applied in an electronic device, selected from the group consisting of a set top box, music player, video player, entertainment unit, navigation device, communications device, personal digital assistant (PDA), fixed location data unit, and a computer, into which the MTJ storage element is integrated.

40. The MTJ storage element according to claim 29 , wherein the MTJ storage element is integrated in a Spin Transfer Torque Magnetoresistive Random Access Memory (STT-MRAM).

41. A method of forming a magnetic tunnel junction (MTJ) storage element, the method comprising:

step for forming a stack comprising a pinned layer and a barrier layer; and

step for forming a composite free layer on top of the barrier layer comprising a first free layer, a nonmagnetic spacer layer and a superparamagnetic layer, such that the spacer layer is interspersed between the first free layer and the superparamagnetic layer.

42. The method of claim 41 , further comprising coupling the first free layer and the superparamagnetic layer via interlayer exchange coupling.

43. The method of claim 42 , wherein a magnetic polarization of the first free layer is aligned parallel to a magnetic polarization of the superparamagnetic layer.

44. The method of claim 42 , wherein a magnetic polarization of the first free layer is aligned anti-parallel to a magnetic polarization of the superparamagnetic layer.

45. The method of claim 41 , further comprising coupling the first free layer the superparamagnetic layer via interlayer fringe coupling.

46. The method of claim 45 , wherein a magnetic polarization of the first free layer is aligned anti-parallel to a magnetic polarization of the superparamagnetic layer.

47. The method of claim 41 , wherein the superparamagnetic layer is formed by reducing the thickness of a ferromagnetic or antiferromagnetic layer.

48. The method of claim 41 , wherein the superparamagnetic layer is formed by doping a nonmagnetic material with ferromagnetic elements.

49. The method of claim 41 , wherein the superparamagnetic layer is formed by doping a ferromagnetic material with nonmagnetic elements.

50. The method of claim 41 , wherein the superparamagnetic layer is formed by interspersing one or more layers of nonmagnetic elements with one or more layers of ferromagnetic elements.

51. The method according to claim 41 , wherein the MTJ storage element is applied in an electronic device, selected from the group consisting of a set top box, music player, video player, entertainment unit, navigation device, communications device, personal digital assistant (PDA), fixed location data unit, and a computer, into which the MTJ storage element is integrated.

52. The method according to claim 41 , wherein the MTJ storage element is integrated in a Spin Transfer Torque Magnetoresistive Random Access Memory (STT-MRAM).