CPP sensor with dual self-pinned AP pinned layer structures

• US 6,781,798 B2
• Filed: 07/15/2002
• Issued: 08/24/2004
• Est. Priority Date: 07/15/2002
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Gill, Hardayal Singh
• Primary Examiner(s): Heinz, A. J.
• Assistant Examiner(s): CASTRO, ANGEL A
• Application Number:
  US10/196,310
• Publication Number:
  US 20040008450A1
• Time in Patent Office: 771 Days
• Field of Search: 360/314, 360/324.11, 360/324.12, 360/324.2
• US Class Current: 360/314
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G11B 2005/0008 Magnetic conditionning of heads, e.g. biasing
• CPC Class Codes: G11B 2005/3996 large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: G11B 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: G11B 5/3932 Magnetic biasing films
• CPC Class Codes: G11B 5/3954 the active elements transducing on a single track
• CPC Class Codes: G11B 5/3967 Composite structural arrangements of transducers, e.g. inductive write and magnetoresistive read G11B5/3906 takes precedence

Abstract

A CPP sensor includes a free layer which is located between first and second spacer layers and the first and second spacer layers are located between first and second AP pinned layer structures. Each of the AP pinned layer structures has first and second AP pinned layers with the first AP pinned layer of the first AP pinned layer structure interfacing the first spacer layer and the first AP pinned layer of the second AP pinned layer structure interfacing the second spacer layer. The second AP pinned layer of each of the first and second AP pinned layer structures is composed of a material which causes each AP pinned layer structure to be self-pinned. This eliminates the need for first and second antiferromagnetic (AFM) pinning layers so that the gaps of a read head employing the sensor and the resistance of the sensor are reduced to increase the linear read bit density of the read head and the magnetoresistive coefficient of the sensor respectively.

Claims

1. A magnetic head assembly, which has a head surface for facing a magnetic medium, comprising:

a CPP sensor including;

first and second antiparallel (AP) pinned layer structures wherein each AP pinned layer structure is self pinned without the assistance of a pinning layer;

each of the first and second AP pinned layer structures having at least first and second antiparallel (AP) pinned layers and at least one antiparallel (AP) coupling layer with the AP coupling layer being located between the first and second AP pinned layers;

a free layer that has a magnetic moment that is oriented parallel to the head surface and parallel to major planes of the AP pinned layers;

a first spacer layer located between the first AP pinned layer structure and the free layer and a second spacer layer located between the second AP pinned layer structure and the free layer;

the first AP pinned layer of the first AP pinned layer structure interfacing the first spacer layer and the first AP pinned layer of the second AP pinned layer structure interfacing the second spacer layer;

each of the first and second AP pinned layers having a magnetic moment that is oriented perpendicular to the head surface; and

the magnetic moments of the first AP pinned layers of the first and second AP pinned layer structures being parallel with respect to one another and in a same direction, the magnetic moments of second AP pinned layers of the first and second AP pinned layer structures being parallel with respect to one another and in a same direction and the magnetic moments of the first AP pinned layers being antiparallel to the magnetic moments of the second AP pinned layers.

2. A magnetic head assembly as claimed in claim 1 wherein each of the second AP pinned layers is composed of a material that has a high magnetocrystalline anisotropy.

3. A magnetic head assembly as claimed in claim 2 wherein each of the second AP pinned layers is composed of a material that is selected from the group consisting of Co, Co₇₅Pt₂₅ and Co₈₀Sm₂₀.

4. A magnetic head assembly as claimed in claim 3 wherein the first and second spacer layers are composed of copper or the first and second spacer layers are composed of aluminum oxide.

5. A magnetic head assembly as claimed in claim 4 further comprising:

a write head including;

ferromagnetic first and second pole piece layers which each have a yoke portion located between a pole tip portion and a back gap portion;

a nonmagnetic write gap layer located between the pole tip portions of the first and second pole piece layers;

an insulation stack with at least one coil layer embedded therein located between the yoke portions of the first and second pole piece layers; and

the first and second pole piece layers being connected at their back gap portions.

6. A magnetic head assembly as claimed in claim 1 wherein each of the second AP pinned layers is composed of a material that has a high magnetostriction.

7. A magnetic head assembly as claimed in claim 6 wherein each of the second AP pinned layers is composed of a material that is selected from the group consisting of Co₅₀Fe₅₀ and Ni₄₅Fe₅₅.

8. A magnetic head assembly as claimed in claim 7 wherein the first and second spacer layers are composed of copper or the first and second spacer layers are composed of aluminum oxide.

9. A magnetic head assembly as claimed in claim 8 further comprising:

a write head including;

ferromagnetic first and second pole piece layers which each have a yoke portion located between a pole tip portion and a back gap portion;

a nonmagnetic write gap layer located between the pole tip portions of the first and second pole piece layers;

an insulation stack with at least one coil layer embedded therein located between the yoke portions of the first and second pole piece layers; and

the first and second pole piece layers being connected at their back gap portions.

10. A magnetic disk drive that has a head surface for facing a magnetic medium and that has at least one magnetic head assembly that includes a write head and a read head comprising:

the write head including;

ferromagnetic first and second pole piece layers that each have a yoke portion located between a pole tip portion and a back gap portion;

a nonmagnetic write gap layer located between the pole tip portions of the first and second pole piece layers;

an insulation stack with at least one coil layer embedded therein located between the yoke portions of the first and second pole piece layers; and

the first and second pole piece layers being connected at their back gap portions;

the read head including;

ferromagnetic first and second shield layers; and

a CPP sensor located between the first and second shield layers;

the CPP sensor including;

first and second antiparallel (AP) pinned layer structures wherein each AP pinned layer structure is self pinned without the assistance of a pinning layer;

each of the first and second AP pinned layer structures having at least first and second antiparallel (AP) pinned layers and at least one antiparallel (AP) coupling layer with the AP coupling layer being located between the first and second AP pinned layers;

a free layer that has a magnetic moment that is oriented parallel to the head surface and parallel to major planes of the AP pinned layers;

a first spacer layer located between the first AP pinned layer structure and the free layer and a second spacer layer located between the second AP pinned layer structure and the free layer;

the first AP pinned layer of the first AP pinned layer structure interfacing the first spacer layer and the first AP pinned layer of the second AP pinned layer structure interfacing the second spacer layer;

each of the first and second AP pinned layers having a magnetic moment that is oriented perpendicular to the head surface; and

the magnetic moments of the first AP pinned layers of the first and second AP pinned layer structures being parallel with respect to one another and in a same direction, the magnetic moments of second AP pinned layers of the first and second AP pinned layer structures being parallel with respect to one another and in a same direction and the magnetic moments of the first AP pinned layers being antiparallel to the magnetic moments of the second AP pinned layers;

a housing;

the magnetic medium being supported in the housing;

a support mounted in the housing for supporting the magnetic head assembly with said head surface facing the magnetic medium so that the magnetic head assembly is in a transducing relationship with the magnetic medium;

a motor for moving the magnetic medium; and

a processor connected to the magnetic head assembly and to the motor for exchanging signals with the magnetic head assembly and for controlling movement of the magnetic medium.

11. A magnetic disk drive as claimed in claim 10 wherein each of the second AP pinned layers is composed of a material that has a high magnetocrystalline anisotropy.

12. A magnetic disk drive as claimed in claim 11 wherein each of the second AP pinned layers is composed of a material that is selected from the group consisting of Co, Co₇₅Pt₂₅ and Co₈₀Sm₂₀.

13. A magnetic disk drive as claimed in claim 12 wherein the first and second spacer layers are composed of copper or the first and second spacer layers are composed of aluminum oxide.

14. A magnetic disk drive as claimed in claim 10 wherein each of the second AP pinned layers is composed of a material that has a high magnetostriction.

15. A magnetic disk drive as claimed in claim 14 wherein each of the second AP pinned layers is composed of a material that is selected from the group consisting of Co₅₀Fe₅₀ and Ni₄₅Fe₅₅.

16. A magnetic disk drive as claimed in claim 15 wherein the first and second spacer layers are composed of copper or the first and second spacer layers are composed of aluminum oxide.

17. A method of making a magnetic head assembly that has a head surface for facing a magnetic medium, comprising the steps of:

a method of making a CPP sensor including the steps of;

forming first and second antiparallel (AP) pinned layer structures wherein each AP pinned layer structure is self pinned without the assistance of a pinning layer;

forming each of the first and second AP pinned layer structures with at least first and second antiparallel (AP) pinned layers and at least one antiparallel (AP) coupling layer with the AP coupling layer being located between the first and second AP pinned layers;

forming a free layer that has a magnetic moment that is oriented parallel to the head surface and parallel to major planes of the AP pinned layers;

forming a first spacer layer between the first AP pinned layer structure and the free layer and forming a second spacer layer between the second AP pinned layer structure and the free layer;

forming the first AP pinned layer of the first AP pinned layer structure interfacing the first spacer layer and the first AP pinned layer structure of the second AP pinned layer structure interfacing the second spacer layer;

forming each of the first and second AP pinned layers with a magnetic moment that is oriented perpendicular to the head surface; and

forming the magnetic moments of the first AP pinned layers of the first and second AP pinned layer structures parallel with respect to one another and in a same direction, the magnetic moments of second AP pinned layers of the first and second AP pinned layer structures parallel with respect to one another and in a same direction and the magnetic moments of the first AP pinned layers antiparallel to the magnetic moments of the second AP pinned layers.

18. A method as claimed in claim 17 wherein each of the second AP pinned layers is formed of a material that has a high magnetocrystalline anisotropy.

19. A method as claimed in claim 18 wherein each of the second AP pinned layers is formed of a material that is selected from the group consisting of Co, Co₇₅Pt₂₅ and Co₈₀Sm₂₀.

20. A method as claimed in claim 19 further comprising the steps of:

a method of making a write head comprising the steps of;

forming ferromagnetic first and second pole piece layers which each have a yoke portion located between a pole tip portion and a back gap portion;

forming a nonmagnetic write gap layer located between the pole tip portions of the first and second pole piece layers;

forming an insulation stack with at least one coil layer embedded therein between the yoke portions of the first and second pole piece layers; and

connecting the first and second pole piece layers at their back gap portions.

21. A method as claimed in claim 17 wherein each of the second AP pinned layers is formed of a material that has a high magnetostriction.

22. A method as claimed in claim 21 wherein each of the second AP pinned layers is formed of a material that is selected from the group consisting of Co₅₀Fe₅₀ and Ni₄₅Fe₅₅.

23. A method as claimed in claim 22 further comprising the steps of:

a method of making a write head comprising the steps of;

forming ferromagnetic first and second pole piece layers which each have a yoke portion located between a pole tip portion and a back gap portion;

forming a nonmagnetic write gap layer located between the pole tip portions of the first and second pole piece layers;

forming an insulation stack with at least one coil layer embedded therein between the yoke portions of the first and second pole piece layers; and

connecting the first and second pole piece layers at their back gap portions.

24. A magnetic head assembly, that has a head surface for facing a magnetic medium, comprising:

a read head that includes a CPP sensor;

the CPP sensor including;

an antiparallel (AP) pinned layer structure;

a ferromagnetic free layer having a magnetic moment that is free to rotate in response to a field signal; and

a spacer layer located between the free layer and the AP pinned layer structure;

the antiparallel (AP) pinned layer structure including;

ferromagnetic first and second antiparallel (AP) pinned layers;

an antiparallel coupling (APC) layer located between and interfacing the first and second AP pinned layers;

the first and second AP pinned layers self pinning one another without assistance of an antiferromagnetic (AFM) pinning layer; and

first and second leads connected to the sensor for conducting a current through the sensor perpendicular to major planes of the layers of the sensor.

25. A magnetic head assembly as claimed in claim 24 wherein the second AP pinned layer is composed of a material that has a high magnetocrystalline anisotropy.

26. A magnetic head assembly as claimed in claim 25 wherein the second AP pinned layer is composed of a material that is selected from the group consisting of Co, Co₇₅Pt₂₅ and Co₈₀Sm₂₀.

27. A magnetic head assembly as claimed in claim 26 wherein the first AP pinned layer is composed of Co₉₀Fe₁₀.

28. A magnetic head assembly as claimed in claim 27 further comprising:

a write head including;

ferromagnetic first and second pole piece layers that have a yoke portion located between a pole tip portion and a back gap portion;

a nonmagnetic write gap layer located between the pole tip portions of the first and second pole piece layers;

an insulation stack with at least one coil layer embedded therein located between the yoke portions of the first and second pole piece layers; and

the first and second pole piece layers being connected at their back gap portions.

29. A magnetic head assembly as claimed in claim 24 wherein the second AP pinned layer is composed of a material that has a high magnetostriation.

30. A magnetic head assembly as claimed in claim 29 wherein the second AP pinned layer is composed of a material that is selected from the group consisting of Co₅₀Fe₅₀ and Ni₄₅Fe₅₅.

31. A magnetic head assembly as claimed in claim 30 wherein the first AP pinned layer is composed of Co₉₀Fe₁₀.

32. A magnetic head assembly as claimed in claim 31 further comprising:

a write head including;

ferromagnetic first and second pole piece layers that have a yoke portion located between a pole tip portion and a back gap portion;

a nonmagnetic write gap layer located between the pole tip portions of the first and second pole piece layers;

an insulation stack with at least one coil layer embedded therein located between the yoke portions of the first and second pole piece layers; and

the first and second pole piece layers being connected at their back gap portions.

33. A magnetic disk drive including at least one magnetic head assembly that has a head surface for facing a magnetic medium and that includes a write head and a read head, comprising:

the write head including;

ferromagnetic first and second pole piece layers that have a yoke portion located between a pole tip portion and a back gap portion;

a nonmagnetic write gap layer located between the pole tip portions of the first and second pole piece layers;

an insulation stack with at least one coil layer embedded therein located between the yoke portions of the first and second pole piece layers; and

the first and second pole piece layers being connected at their back gap portions;

the read head including;

ferromagnetic first and second shield layers; and

a CPP sensor located between the first and second shield layers;

the CPP sensor including;

an antiparallel (AP) pinned layer structure;

a ferromagnetic free layer having a magnetic moment that is free to rotate in response to a field signal; and

a spacer layer located between the free layer and the AP pinned layer structure;

the antiparallel (AP) pinned layer structure including;

 

ferromagnetic first and second antiparallel (AP) pinned layers;

 

an antiparallel coupling (APC) layer located between and interfacing the first and second AP pinned layers;

 

the first and second AP pinned layers self pinning one another without assistance of an antiferromagnetic (AFM) pinning layer; and

 

first and second leads connected to the sensor for conducting a current through the sensor perpendicular to major planes of the layers of the sensor;

a housing;

the magnetic medium being supported in the housing;

a support mounted in the housing for supporting the magnetic head assembly with said head surface facing the magnetic medium so that the magnetic head assembly is in a transducing relationship with the magnetic medium;

a motor for moving the magnetic medium; and

a processor connected to the magnetic head assembly and to the motor for exchanging signals with the magnetic head assembly and for controlling movement of the magnetic medium.

34. A magnetic disk drive as claimed in claim 33 wherein the second AP pinned layer is composed of a material that has a high magnetocrystalline anisotropy.

35. A magnetic disk drive as claimed in claim 33 wherein the second AP pinned layer is composed of a material that has a high magnetostriction.

36. A method of making a magnetic head assembly, which has a head surface for facing a magnetic medium, comprising the steps of:

forming a read head that includes a CPP sensor;

a making of the CPP sensor including the steps of;

forming an antiparallel (AP) pinned layer structure;

forming a ferromagnetic free layer that has a magnetic moment that is free to rotate in response to a field signal; and

forming a spacer layer between the free layer and the AP pinned layer structure;

the forming of the antiparallel (AP) pinned layer structure including the steps of;

forming ferromagnetic first and second antiparallel (AP) pinned layers;

forming an antiparallel coupling (APC) layer between and interfacing the first and second AP pinned layers;

the first and second AP pinned layers being further formed to self pin one another without assistance of an antiferromagnetic (AFM) pinning layer; and

forming first and second leads connected to the sensor for conducting a current through the sensor perpendicular to major planes of the layers of the sensor.

37. A method as claimed in claim 36 wherein each of the second AP pinned layers is formed of a material that has a high magnetocrystalline anisotropy.

38. A method as claimed in claim 37 wherein the second AP pinned layer is formed of a material that is selected from the group consisting of Co, Co₇₅Pt₂₅ and Co₈₀Sm₂₀.

39. A method as claimed in claim 38 wherein the first AP pinned layer is formed of Co₉₀Fe₁₀.

40. A method as claimed in claim 36 wherein the second AP pinned layer is formed of a material that has a high magnetostriction.

41. A method as claimed in claim 40 wherein the second AP pinned layer is formed of a material that is selected from the group consisting of Co₅₀Fe₅₀ and Ni₄₅Fe₅₅.

42. A method as claimed in claim 41 wherein the first AP pinned layer is formed of Co₉₀Fe₁₀.