Magnetoresistive element having reduced spin transfer induced noise

• US 20050041342A1
• Filed: 05/05/2004
• Published: 02/24/2005
• Est. Priority Date: 08/21/2003
• Status: Active Grant

• Current Assignee: Samsung Semiconductor Incorporated (Samsung Electronics Co. Ltd.)
• Original Assignee: Grandis, Inc. (Samsung Electronics Co. Ltd.)
• Inventors: Nguyen, Paul P., Huai, Yiming
• Granted Patent: US 7,245,462 B2
• Time in Patent Office: Days
• US Class Current: 360/324.120
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G11B 5/127 Structure or manufacture of heads, e.g. inductive
• CPC Class Codes: G11B 5/33 Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing onlySingle head using magnetic domains for scanning G11B5/4946; multiple head for scanning G11B5/4907 and subgroups ; general details therefor G11B5/133 - G11B5/255

Abstract

A method and system for providing a magnetic element is disclosed. The method and system include providing a ferromagnetic pinned layer, providing a free layer, and providing a spacer layer between the pinned layer and the free layer. The pinned layer and free layer are ferromagnetic and have a pinned layer magnetization and a free layer magnetization, respectively. The spacer layer is nonmagnetic. In one aspect, the free layer is configured to have an increased magnetic damping constant. In another aspect, the method and system also include providing a second pinned layer and a second spacer layer between the free layer and the second pinned layer. In this aspect, the first pinned layer and/or the second pinned layer are configured such that a forward torque and a reflected torque due to a current driven through the magnetic element in a current-perpendicular-to-plane configuration are substantially equal and opposite.

Claims

1. A magnetic element comprising:

a pinned layer being ferromagnetic and having a pinned layer magnetization;

a spacer layer, the spacer layer being nonmagnetic; and

a free layer, the spacer layer residing between the pinned layer and the free layer, the free layer being ferromagnetic and having a free layer magnetization, the free layer being configured to have an increased magnetic damping constant.

2. The magnetic element of claim 1 wherein the free layer includes CoFeCuX where X is Tb, Gd, Pt, Ta, Os, Nb, Rh, or Ru.

3. The magnetic element of claim 2 wherein X is less than or equal to five atomic percent of Tb, Gd, Pt, Ta, Os, Nb, Rh, or Ru.

4. The magnetic element of claim 2 wherein the free layer further includes an insertion layer including at least one ferromagnetic material.

5. The magnetic element of claim 2 wherein the free layer is a synthetic free layer.

6. The magnetic element of claim 2 wherein the pinned layer is a synthetic pinned layer.

7. The magnetic element of claim 2 further comprising a second spacer layer and a second pinned layer, the second spacer layer residing between the second pinned layer and the free layer.

8. The magnetic element of claim 7 wherein the free layer further includes a first insertion layer including at least one ferromagnetic material, the first insertion layer residing between the free layer and the pinned layer or the second pinned layer.

9. The magnetic element of claim 8 wherein the at least one ferromagnetic material includes Co, Ni, Fe, and/or alloys of Co, Ni, Fe.

10. The magnetic element of claim 8 wherein the free layer further includes a second insertion layer including at least a second insertion layer, the second insertion layer residing between the free layer and an other of the pinned layer and the second pinned layer.

11. The magnetic element of claim 7 wherein the pinned layer is a first synthetic pinned layer including a first ferromagnetic layer having a first magnetization, a second ferromagnetic layer having a second magnetization, and a first nonmagnetic spacer layer between the first ferromagnetic layer and the second ferromagnetic layer, the first nonmagnetic spacer layer being configured so that the first magnetization and the second magnetization are antiferromagnetically aligned;

and

wherein the second pinned layer is a second synthetic pinned layer including a third ferromagnetic layer having a third magnetization, a fourth ferromagnetic layer having a fourth magnetization, and a second nonmagnetic spacer layer between the third ferromagnetic layer and the fourth ferromagnetic layer, the second nonmagnetic spacer layer being configured so that the third magnetization and the fourth magnetization are antiferromagnetically aligned.

12. The magnetic element of claim 11 wherein the second ferromagnetic layer is closer to the free layer than the first ferromagnetic layer, wherein the third ferromagnetic layer is closer to the free layer than the fourth ferromagnetic layer, and wherein the second ferromagnetic layer and/or the third ferromagnetic layer are configured such that a forward torque and a reflected torque due to a current driven through the magnetic element in a current-perpendicular-to-plane (CPP) configuration are substantially equal and opposite.

13. The magnetic element of claim 12 wherein the third pinned layer further includes a spin depolarization layer, the spin depolarization layer being configured to depolarize at least a portion of a plurality of electrons passing through the spin depolarization layer.

14. A magnetic element comprising:

a first pinned layer being a first synthetic pinned layer including a first ferromagnetic layer having a first magnetization, a second ferromagnetic layer having a second magnetization, and a first nonmagnetic spacer layer between the first ferromagnetic layer and the second ferromagnetic layer, the first nonmagnetic spacer layer being configured so that the first magnetization and the second magnetization are antiferromagnetically aligned; and

a first spacer layer, the first spacer layer being nonmagnetic;

a free layer being ferromagnetic and having a free layer magnetization, the first spacer layer residing between the first pinned layer and the free layer, the second ferromagnetic layer being closer to the free layer than the first ferromagnetic layer;

a second spacer layer, the second spacer layer being nonmagnetic;

a second pinned layer, the second spacer layer residing between the second pinned layer and the free layer, the second pinned layer being a second synthetic pinned layer including a third ferromagnetic layer having a third magnetization, a fourth ferromagnetic layer having a fourth magnetization, and a second nonmagnetic spacer layer between the third ferromagnetic layer and the fourth ferromagnetic layer, the second nonmagnetic spacer layer being configured so that the third magnetization and the fourth magnetization are antiferromagnetically aligned, the third ferromagnetic layer being closer to the free layer than the fourth ferromagnetic layer;

the first pinned layer and/or the second pinned layer being configured such that a forward torque and a reflected torque due to a current driven through the magnetic element in a current-perpendicular-to-plane (CPP) configuration are substantially equal and opposite.

15. The magnetic element of claim 14 wherein the second ferromagnetic layer and/or the third ferromagnetic layer are configured such that the forward torque and the reflected torque due to the current driven through the magnetic element in the CPP configuration are substantially equal.

16. The magnetic element of claim 14

wherein the first pinned layer and/or the second pinned layer include a spin depolarization layer configured to depolarize at least a portion of a plurality of electrons passing through the spin depolarization layer.

17. The magnetic element of claim 16 wherein the spin depolarization layer resides within the third ferromagnetic layer.

18. The magnetic element of claim 16 wherein the spin depolarization layer resides between the third or fourth ferromagnetic layer and the second nonmagnetic spacer layer.

19. The magnetic element of claim 16 wherein the spin depolarization layer resides within the second ferromagnetic layer.

20. The magnetic element of claim 16 wherein the spin depolarization layer resides between the second or first ferromagnetic layer and the first nonmagnetic spacer layer.

21. The magnetic element of claim 14 wherein the free layer is a synthetic free layer.

22. The magnetic element of claim 14 wherein the free layer includes CoFeCuX where X is Tb, Gd, Pt, Ta, Os, Nb, Rh, or Ru.

23. A method for providing a magnetic element comprising:

(a) providing a pinned layer being ferromagnetic and having a pinned layer magnetization;

(b) providing a spacer layer, the spacer layer being nonmagnetic; and

(c) providing a free layer, the spacer layer residing between the pinned layer and the free layer, the free layer being ferromagnetic and having a free layer magnetization, the free layer being configured to have an increased magnetic damping constant.

24. The method of claim 23 wherein the free layer providing step (c) further includes the step of:

(c1) providing at least one layer of CoFeCuX where X is Tb, Gd, Pt, Ta, Os, Nb, Rh,or Ru.

25. A method for providing a magnetic element comprising:

(a) providing a first pinned layer being a first synthetic pinned layer including a first ferromagnetic layer having a first magnetization, a second ferromagnetic layer having a second magnetization, and a first nonmagnetic spacer layer between the first ferromagnetic layer and the second ferromagnetic layer, the first nonmagnetic spacer layer being configured so that the first magnetization and the second magnetization are antiferromagnetically aligned; and

(b) providing a first spacer layer, the first spacer layer being nonmagnetic;

(c) providing a free layer being ferromagnetic and having a free layer magnetization, the first spacer layer residing between the first pinned layer and the free layer, the second ferromagnetic layer being closer to the free layer than the first ferromagnetic layer;

(d) providing a second spacer layer, the first spacer layer being nonmagnetic;

(e) providing a second pinned layer, the second spacer layer residing between the second pinned layer and the free layer, the second pinned layer being a second synthetic pinned layer including a third ferromagnetic layer having a third magnetization, a fourth ferromagnetic layer having a fourth magnetization, and a second nonmagnetic spacer layer between the third ferromagnetic layer and the fourth ferromagnetic layer, the second nonmagnetic spacer layer being configured so that the third magnetization and the fourth magnetization are antiferromagnetically aligned, the third ferromagnetic layer being closer to the free layer than the fourth ferromagnetic layer;

the first pinned layer and/or the second pinned layer being configured such that a forward torque and a reflected torque due to a current driven through the magnetic element in a current-perpendicular-to-plane (CPP) configuration are substantially equal and opposite.