Dual hybrid magnetic tunnel junction/giant magnetoresistive sensor

• US 6,473,275 B1
• Filed: 06/06/2000
• Issued: 10/29/2002
• Est. Priority Date: 06/06/2000
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Gill, Hardayal (Harry) Singh
• Primary Examiner(s): Miller, Brian E.
• Application Number:
  US09/588,849
• Time in Patent Office: 875 Days
• Field of Search: 365/145, 365/171-173, 360/314, 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: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G01R 33/098 comprising tunnel junctions, e.g. tunnel magnetoresistance sensors
• 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 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: G11B 5/3951 the active elements being arranged on several parallel planes
• CPC Class Codes: G11B 5/3967 Composite structural arrangements of transducers, e.g. inductive write and magnetoresistive read G11B5/3906 takes precedence

Abstract

A dual hybrid magnetic tunnel junction (MTJ)/giant magnetoresistance (GMR) sensor is provided having an MTJ stack, a GMR stack and a common free layer. The MTJ stack includes a first antiferromagnetic (AFM) layer, an first antiparallel (AP)-pinned layer and a tunnel barrier layer. The GMR stack, operating in the current perpendicular to the plane (CPP) mode, includes a second AFM layer, a second AP-pinned layer and a spacer layer. The first and second AFM layers are set to pin the magnetizations of the first and second AP-pinned layers perpendicular to the ABS and in the same direction with respect to each other resulting in an additive response to a signal field of the MTJ and GMR stacks. The thickness of the spacer layer in the GMR stack is chosen to provide a negative ferromagnetic coupling field between the second AP-pinned layer and the free layer which opposes the positive ferromagnetic coupling field between the first AP-pinned layer and the free layer across the tunnel barrier layer. The net ferromagnetic coupling field at the free layer can be reduced to a small value resulting in an improved bias point for the free layer of the MTJ/GMR sensor.

Claims

1. A dual hybrid magnetic tunnel junction (MTJ)/giant magnetoresisive (GMR) sensor, comprising:

an MTJ stack, including a first AP-pinned layer and a tunnel barrier layer, said tunnel barrier layer adjacent to and in contact with said first AP-pinned layer;

a GMR stack, including a second AP-pinned layer and a spacer layer, said spacer layer adjacent to and in contact with said second AP-pinned layer; and

a ferromagnetic free layer disposed between the tunnel barrier layer and the spacer layer.

2. The dual hybrid MTJ/GMR sensor as recited in claim 1 wherein said MTJ stack further comprises a first AFM layer adjacent to said first AP-pinned layer.

3. The dual hybrid MTJ/GMR sensor as recited in claim 2 wherein said first AFM layer is made of Pt—

Mn.

4. The dual hybrid MTJ/GMR sensor as recited in claim 2 wherein said first AFM layer is selected from the group of materials consisting of Pt—

Mn, Ir—

Mn, Pt—

Pd—

Mn, and Ni—

Mn.

5. The dual hybrid MTJ/GMR sensor as recited in claim 1 wherein said GMR stack further comprises a second AFM layer adjacent to said second AP-pinned layer.

6. The dual hybrid MTJ/GMR sensor as recited in claim 5 wherein said second AFM layer is made of Pt—

Mn.

7. The dual hybrid MTJ/GMR sensor as recited in claim 5 wherein said first AFM layer is selected from the group of materials consisting of Pt—

Mn, Ir—

Mn, Pt—

Pd—

Mn, and Ni—

Mn.

8. The dual hybrid MTJ/GMR sensor as recited in claim 1 wherein said tunnel barrier layer is made of Al₂O₃.

9. The dual hybrid MTJ/GMR sensor as recited in claim 1 wherein said spacer layer is made of copper (Cu).

10. The dual hybrid MTJ/GMR sensor as recited in claim 9 wherein said spacer layer has a thickness in the range 19-24 Å

, said spacer layer providing negative ferromagnetic coupling between said second AP-pinned layer and said free layer.

11. The dual hybrid MTJ/GMR sensor as recited in claim 1 wherein said first AP-pinned layer comprises:

a first ferromagnetic (FM) layer;

a second FM layer adjacent to said tunnel barrier layer; and

an antiparallel coupling (APC) layer disposed between said first and second FM layers.

12. The dual hybrid MTJ/GMR sensor as recited in claim 11 wherein said first and second FM layers are made of Co—

Fe.

13. The dual hybrid MTJ/GMR sensor as recited in claim 11 wherein said APC layer is made of ruthenium (Ru).

14. The dual hybrid MTJ/GMR sensor as recited in claim 1 wherein said second AP-pinned layer comprises:

a third FM layer in contact with said spacer layer;

a fourth FM layer; and

an APC layer disposed between said third and fourth FM layers.

15. The dual hybrid MTJ/GMR sensor as recited in claim 13 wherein said third and fourth FM layers are made of Co—

Fe.

16. The dual hybrid MTJ/GMR sensor as recited in claim 14 wherein said APC layer is made of ruthenium (Ru).

17. A dual hybrid magnetic tunnel junction (MTJ)/giant magnetoresisive (GMR) sensor, comprising:

an MTJ stack including;

A first AFM layer;

a first AP-pinned layer comprising;

a first ferromagnetic (FM) layer;

a second FM layer; and

an antiparallel coupling (APC) layer disposed between said first and second FM layers;

a tunnel barrier layer, said tunnel barrier layer adjacent to and in contact with said second FM layer;

a GMR stack including;

a second AFM layer;

a second AP-pinned layer comprising;

a fourth FM layer in contact with said second AFM layer;

a third FM layer; and

an APC layer disposed between said third and fourth FM layers; and

a spacer layer, said spacer layer adjacent to and in contact with said third FM layer; and

a ferromagnetic free layer disposed between the tunnel barrier layer and the spacer layer.

18. The dual hybrid MTJ/GMR sensor as recited in claim 17 wherein said first and second AFM layers are made of Pt—

Mn.

19. The dual hybrid MTJ/GMR sensor as recited in claim 17 wherein said first and second AFM layers are selected from the group of materials consisting of Pt—

Mn, Ir—

Mn, Pt—

Pd—

Mn, and Ni—

Mn.

20. The dual hybrid MTJ/GMR sensor as recited in claim 17 wherein said tunnel barrier layer is made of Al₂O₃.

21. The dual hybrid MTJ/GMR sensor as recited in claim 17 wherein said spacer layer is made of copper (Cu).

22. The dual hybrid MTJ/GMR sensor as recited in claim 21 wherein said spacer layer has a thickness in the range 19-24 Å

, said spacer layer providing negative ferromagnetic coupling between said third FM layer and said free layer.

23. The dual hybrid MTJ/GMR sensor as recited in claim 17 wherein said first, second, third and fourth FM layers are made of Co—

Fe.

24. The dual hybrid MTJ/GMR sensor as recited in claim 17 wherein said APC layers are made of ruthenium (Ru).

25. A dual hybrid magnetic tunnel junction (MTJ)/giant magnetoresisive (GMR) sensor, comprising:

an MTJ stack including;

an first AFM layer;

a first AP-pinned layer comprising;

a first ferromagnetic (FM) layer;

a second FM layer; and

an antiparallel coupling (APC) layer disposed between said first and second FM layers;

a tunnel barrier layer, said tunnel barrier layer adjacent to and in contact with said second FM layer;

a GMR stack including;

a second AMR layer;

a second AP-pinned layer comprising;

a fifth FM layer in contact with said second AFM layer;

a fourth FM layer;

an APC layer disposed between said fourth and fifth FM layers;

a third FM layer; and

an APC layer disposed between said third and fourth FM layers;

a spacer layer, said spacer layer adjacent to and in contact with said third FM layer; and

a ferromagnetic free layer disposed between the tunnel barrier layer and the spacer layer, said free layer comprising;

a ferromagnetic first sense layer adjacent to said tunnel barrier layer;

a ferromagnetic second sense layer; and

an APC layer layer disposed between said first and second sense layers.

26. The dual hybrid MTJ/GMR sensor as recited in claim 25 wherein said first and second AFM layers are made of Pt—

Mn.

27. The dual hybrid MTJ/GMR sensor as recited in claim 25 wherein said first and second AFM layers are selected from the group of materials consisting of Pt—

Mn, Ir—

Mn, Pt—

Pd—

Mn, and Ni—

Mn.

28. The dual hybrid MTJ/GMR sensor as recited in claim 25 wherein said tunnel barrier layer is made of Al₂O₃.

29. The dual hybrid MTJ/GMR sensor as recited in claim 25 wherein said spacer layer is made of copper (Cu).

30. The dual hybrid MTJ/GMR sensor as recited in claim 29 wherein said spacer layer has a thickness in the range 19-24 Å

said spacer layer providing negative ferromagnetic coupling between said third FM layer and said second sense layer.

31. The dual hybrid MTJ/GMR sensor as recited in claim 25 wherein said FM layers are made of Co—

Fe.

32. The dual hybrid MTJ/GMR sensor as recited in claim 25 wherein said APC layers are made of ruthenium (Ru).

33. A magnetic read/write head, comprising:

a write head including;

at least one coil layer and an insulation stack, the coil layer being embedded in the insulation stack;

first and second pole piece layers connected at a back gap and having pole tips with edges forming a portion of an air bearing surface (ABS);

the insulation stack being sandwiched between the first and second pole piece layers; and

a write gap layer sandwiched between the pole tips of the first and second pole piece layers and forming a portion of the ABS;

a read head including;

a dual hybrid MTJ/GMR sensor and first and second shield layers, the MTJ/GMR sensor being sandwiched between the first and second shield layers, the MTJ/GMR sensor including;

an MTJ stack including;

a first AFM layer;

a first AP-pinned layer comprising;

 

a first ferromagnetic (FM) layer;

 

a second FM layer; and

 

an antiparallel coupling (APC) layer disposed between said first and second FM layers;

 

a tunnel barrier layer, said tunnel barrier layer adjacent to and in contact with said second FM layer;

a GMR stack including;

a second AFM layer;

a second AP-pinned layer comprising;

 

a fourth FM layer in contact with said second AFM layer;

 

a third FM layer; and

 

an APC layer disposed between said third and fourth FM layers; and

a spacer layer, said spacer layer adjacent to and in contact with said third FM layer; and

a ferromagnetic free layer disposed between the tunnel barrier layer and the spacer layer; and

an insulation layer disposed between the second shield layer of the read head and the first pole piece layer of the write head.

34. The magnetic read/write head as recited in claim 33 wherein said first and second AFM layers are made of Pt—

Mn.

35. The magnetic read/write head as recited in claim 33 wherein said first and second AFM layers are selected from the group of materials consisting of Pt—

Mn, Ir—

Mn, Pt—

Pd—

Mn, and Ni—

Mn.

36. The magnetic read/write head as recited in claim 33 wherein said spacer layer is made of copper (Cu).

37. The magnetic read/write head as recited in claim 36 wherein said spacer layer has a thickness in the range 19-24 Å

, said spacer layer providing negative ferromagnetic coupling between said third FM layer and said free layer.

38. A disk drive system comprising:

a magnetic recording disk;

a magnetic read/write head for magnetically recording data on the magnetic recording disk and for sensing magnetically recorded data on the magnetic recording disk, said magnetic read/write head comprising;

a write head including;

at least one coil layer and an insulation stack, the coil layer being embedded in the insulation stack;

first and second pole piece layers connected at a back gap and having pole tips with edges forming a portion of an air bearing surface (ABS);

the insulation stack being sandwiched between the first and second pole piece layers; and

a write gap layer sandwiched between the pole tips of the first and second pole piece layers and forming a portion of the ABS;

a read head including;

a dual hybrid MTJ/GMR sensor and first and second shield layers, the MTJ/GMR sensor being sandwiched between the first and second shield layers, the MTJ/GMR sensor including;

an MTJ stack including;

a first AFM layer;

a first AP-pinned layer comprising;

 

a first ferromagnetic (FM) layer;

 

a second FM layer; and

 

an antiparallel coupling (APC) layer disposed between said first and second FM layers;

a tunnel barrier layer, said tunnel barrier layer adjacent to and in contact with said second FM layer;

a GMR stack including;

a second AFM layer;

a second AP-pinned layer comprising;

 

a fourth FM layer in contact with said second AFM layer;

 

a third FM layer; and

 

an APC layer disposed between said third and fourth FM layers; and

a spacer layer, said spacer layer adjacent to and in contact with said third FM layer; and

a ferromagnetic free layer disposed between the tunnel barrier layer and the spacer layer;

an insulation layer disposed between the second shield layer of the read head and the first pole piece layer of the write head;

an actuator for moving said magnetic read/write head across the magnetic disk so that the read/write head may access different regions of the magnetic recording disk; and

a recording channel coupled electrically to the write head for magnetically recording data on the magnetic recording disk and to the MTJ/GMR sensor of the read head for detecting changes in resistance of the MTJ/GMR sensor caused by rotation of the magnetization axis of the ferromagnetic free layer relative to the fixed magnetizations of the first and second AP-pinned layers in response to magnetic fields from the magnetically recorded data.