Simultaneous fixation of the magnetization direction in a dual GMR sensor's pinned layers

• US 6,181,533 B1
• Filed: 02/19/1999
• Issued: 01/30/2001
• Est. Priority Date: 02/19/1999
• Status: Expired due to Fees

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Pokhil, Taras G.
• Primary Examiner(s): HEINZ, ALLEN J
• Application Number:
  US09/253,806
• Time in Patent Office: 711 Days
• Field of Search: 360/324, 360/324.12, 360/326, 338/32.R, 324/207.21, 324/252
• US Class Current: 360/324
• 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: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• 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 5/3163 Fabrication methods or processes specially adapted for a particular head structure, e.g. using base layers for electroplating, using functional layers for masking, using energy or particle beams for shaping the structure or modifying the properties of the basic layers
• 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 5/3948 the sensitive elements being active read-out elements
• CPC Class Codes: G11B 5/3954 the active elements transducing on a single track
• CPC Class Codes: H01F 10/3263 the exchange coupling being symmetric, e.g. for dual spin valve, e.g. NiO/Co/Cu/Co/Cu/Co/NiO
• CPC Class Codes: H01F 10/3268 the exchange coupling being asymmetric, e.g. by use of additional pinning, by using antiferromagnetic or ferromagnetic coupling interface, i.e. so-called spin-valve [SV] structure, e.g. NiFe/Cu/NiFe/FeMn
• CPC Class Codes: H01F 41/304 using temporary decoupling, e.g. involving blocking, Néel or Curie temperature transitions by heat treatment in presence/absence of a magnetic field

Abstract

The present invention provides a method for forming a dual giant magnetoresistive sensor. First and second spin valves are first formed and arranged such that a dielectric layer is positioned between the first and the second spin valves. The first spin valve has a plurality of layers including a first antiferromagnetic layer and a first pinned layer. The second spin valve has a plurality of layers including a second antiferromagnetic layer and a second pinned layer. First and second currents are supplied respectively to first and second spin valves. The first current generates a first magnetic field on the first pinned layer that orients a magnetization of the first pinned layer in a first desired direction. The second current generates a second magnetic field on the second pinned layer that orients a magnetization of the second antiferromagnetic layer in a second desired direction. While continuing to supply the first and the second currents, the dual giant magnetoresistive sensor is cooled from a temperature greater than N{acute over (e)}el temperatures of both first and second antiferromagnetic layers to a temperature below the N{acute over (e)}el temperature of both first and second antiferromagnetic layers.

Claims

1. A dual giant magnetoresistive read sensor comprising:

first and second spin valves separated by a dielectric layer, the first spin valve having a plurality of layers including a first pinned layer and the second spin valve having a plurality of layers including a second pinned layer; and

means for simultaneously fixing a magnetization of the first pinned layer and a magnetization of the second pinned layer.

2. A method for forming a dual giant magnetoresistive read sensor, the method comprising:

forming first and second spin valves separated by a dielectric layer, the first spin valve having a plurality of layers including a first antiferromagnetic layer exchange coupled to a first pinned layer and the second spin valve having a plurality of layers including a second antiferromagnetic layer exchange coupled to a second pinned layer;

supplying a first current to the first spin valve, the first current generating a first magnetic field on the first pinned layer orienting a magnetization of the first pinned layer in a first desired direction;

supplying a second current to the second spin valve, the second current generating a second magnetic field on the second pinned layer orienting a magnetization ofthe second pinned layer in a second desired direction; and

cooling the dual giant magnetoresistive sensor, while continuing to supply the first and the second currents, from a temperature greater than N{acute over (e)}el temperatures of both the first and the second antiferromagnetic layers to a temperature lower than the N{acute over (e)}el temperatures of both the first and the second antiferromagnetic layers.

3. The method of claim 2 wherein the first and the second spin valves are arranged such that the first antiferromagnetic layer is a furthest layer of each of the plurality of layers ofthe first spin valve from the dielectric layer and the second antiferromagnetic layer is a furthest layer of each of the plurality of layers of the second spin valve from the dielectric layer.

4. The method of claim 2 wherein the first desired direction is antiparallel to the second desired direction.

5. The method of claim 2 wherein an easy axis of a first free layer of the first spin valve is oriented antiparallel to an easy axis of a second free layer of the second spin valve.

6. The method of claim 2 wherein an easy axis of a first free layer of the first spin valve is oriented parallel to an easy axis of a second free layer of the second spin valve.

7. The method of claim 2 wherein the N{acute over (e)}el temperature of the first antiferromagnetic layer substantially equals the N{acute over (e)}el temperature of the second antiferromagnetic layer.

8. A dual giant magnetoresistive read sensor for use in a magnetic storage system, the dual giant magnetoresistive read sensor comprising:

first and second spin valves separated by a dielectric layer, the first spin valve having a plurality of layers including a first antiferromagnetic layer exchange coupled to a first pinned layer and the second spin valve having a plurality of layers including a second antiferromagnetic layer exchange coupled to a second pinned layer; and

wherein the first and the second pinned layers have magnetization directions determined by first and second magnetic fields produced by current flow through the first and the second spin valves, respectively, as the dual giant magnetoresistive sensor was cooled from a temperature greater than N{acute over (e)}el temperatures of both the first and the second antiferromagnetic layers to a temperature lower than the N{acute over (e)}el temperatures of both the first and the second antiferromagnetic layers.

9. The dual giant magnetoresistive read sensor of claim 8 wherein the first and the second spin valves are arranged such that the first antiferromagnetic layer is a furthest layer of each of the plurality of layers of the first spin valve from the dielectric layer and the second antiferromagnetic layer is a furthest layer of each of the plurality of layers of the second spin valve from the dielectric layer.

10. The dual giant magnetoresistive read sensor of claim 8 wherein the first magnetic field oriented the magnetization of the first pinned layer in a first desired direction and the second magnetic field oriented the magnetization of the second pinned layer in a second desired direction antiparallel to the first desired direction.

11. The dual giant magnetoresistive read sensor of claim 8 wherein an easy axis of a first free layer ofthe first spin valve is oriented antiparallel to an easy axis of a second free layer of the second spin valve.

12. The dual giant magnetoresistive read sensor of claim 8 wherein an easy axis of a first free layer of the first spin valve is oriented parallel to an easy axis of a second free layer of the second spin valve.

13. The dual giant magnetoresistive read sensor of claim 8 wherein the N{acute over (e)}el temperature of the first antiferromagnetic layer substantially equals the Neel temperature of the second antiferromagnetic layer.