Heterogeneous spacers for CPP GMR stacks

• US 20020114974A1
• Filed: 02/21/2001
• Published: 08/22/2002
• Est. Priority Date: 02/21/2001
• Status: Active Grant

• Current Assignee: HGST Netherlands B.V. (Western Digital Corporation)
• Original Assignee: Hitachi Global Storage Technologies Netherlands BV (Western Digital Corporation)
• Inventors: Gurney, Bruce Alvin, Childress, Jeffrey Robinson, Carey, Matthew Joseph
• Granted Patent: US 6,686,068 B2
• Time in Patent Office: Days
• US Class Current: 428/692
• 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 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: H01F 10/3227 Exchange coupling via one or more magnetisable ultrathin or granular films
• CPC Class Codes: H01F 10/3259 Spin-exchange-coupled multilayers comprising at least a nanooxide layer [NOL], e.g. with a NOL spacer
• CPC Class Codes: H01F 41/302 for applying spin-exchange-coupled multilayers, e.g. nanostructured superlattices spin-exchange-coupled multilayers H01F10/32
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10T 428/1107 Magnetoresistive
• CPC Class Codes: Y10T 428/1129 Super lattice [e.g., giant magneto resistance [GMR] or colossal magneto resistance [CMR], etc.]

Abstract

A CPP magnetoresistive sensor with a spacer layer made of a heterogeneous material, which is composed of conductive grains within a highly resistive matrix, has a high resistance. The conductive grains are typically made of a conductive element or alloy that can operate as a GMR spacer material. The highly resistive matrix is typically made of a highly resistive or insulating element, alloy or compound that will hinder the flow of electrons. The sensing electrical current is passed through the conductive grains, which are typically made of the same material as GMR spacers, so the GMR is maintained even though the overall resistance is increased.

Claims

1. A current-perpendicular-to-plane (CPP) magnetoresistive sensor comprising:

a) at least two magnetic layers; and

b) at least one spacer layer disposed between the two magnetic layers, wherein the spacer layer comprises a heterogeneous material.

2. The CPP magnetoresistive sensor of claim 1, wherein the heterogeneous material comprises conductive grains.

3. The CPP magnetoresistive sensor of claim 2, wherein the conductive grains comprise a conductive material that operates as a giant magnetoresistive (GMR) spacer material.

4. The CPP magnetoresistive sensor of claim 3, wherein conductive grains comprise a material selected from the group consisting of Cu, Au, Ag and their alloys.

5. The CPP magnetoresistive sensor of claim 4, wherein the content of conductive grains in the spacer layer is between about 0.1 volume % and about 50 volume %.

6. The CPP magnetoresistive sensor of claim 5, wherein the heterogeneous material further comprises a highly resistive matrix.

7. The CPP magnetoresistive sensor of claim 6, wherein the highly resistive matrix comprises a highly resistive material.

8. The CPP magnetoresistive sensor of claim 7, wherein the highly resistive matrix comprises a material with a resistivity greater than 100 μ

Ω

-cm.

9. The CPP magnetoresistive sensor of claim 8, wherein the highly resistive matrix comprises a material selected from the group consisting of Si, NiO, SiO₂ and Al₂O₃.

10. The CPP magnetoresistive sensor of claim 9, wherein the materials of the conductive grains and the highly resistive matrix are immiscible.

11. The CPP magnetoresistive sensor of claim 9, wherein the materials of the conductive grains and the highly resistive matrix have low miscibility.

12. The CPP magnetoresistive sensor of claim 1 wherein at least one of the magnetic layers has a magnetization pinned by an anti-ferromagnetic layer.

14. The method of claim 13, wherein the heterogeneous material comprises conductive grains within a highly resistive matrix.

15. The method of claim 13, wherein the heterogeneous spacer layer is deposited by co-depositing of a conductive material and a highly resistive material, wherein the conductive material and the highly resistive material are immiscible.

16. The method of claim 13, wherein b) comprises the steps of:

i) depositing a heterogeneous material of first and second metals, the first and second metals are immiscible, wherein the first metal resists oxidation; and

ii) oxidizing the second metal.

17. The method of claim 13, wherein b) comprises the steps of:

i) depositing a layer of a conductive material; and

ii) depositing a discontinuous layer of a highly resistive material on top of the layer of conductive material.

18. The method of claim 13, wherein b) comprises the steps of:

i) depositing a first metal layer, wherein the first metal layer resists oxidation;

ii) depositing a discontinuous second metal layer on top of the first metal layer; and

iii) oxidizing the discontinuous second metal layer.

19. The method of claim 13, wherein b) comprises the steps of:

i) depositing a homogeneous metal layer; and

ii) partially oxidizing the homogeneous metal layer.

13. A method of making a CPP magnetoresistive sensor comprising:

a) depositing a first magnetic layer;

b) depositing a spacer layer in proximity to the first magnetic layer, wherein the spacer layer comprises a heterogeneous material; and

c) depositing a second magnetic layer in proximity to the spacer layer, wherein the spacer layer is disposed between the first and second magnetic layers.

20. A CPP GMR read/write head comprising:

a) a first shield;

b) a first conductive gap adjacent to the first shield;

c) a second shield;

d) a second conductive gap adjacent to the second shield; and

e) a CPP magnetoresitive sensor disposed between the first and second conductive gaps;

wherein the CPP magnetoresistive sensor comprises;

i) at least two magnetic layers; and

ii) at least one spacer layer disposed between the two magnetic layers, wherein the spacer layer comprises a heterogeneous material.

21. The CPP GMR read/write head of claim 20, wherein the heterogeneous material comprises conductive grains within a highly resistive matrix.

22. A disk drive comprising:

a) a magnetic recording disk;

b) a CPP GMR read/write head including a CPP magnetoresistive sensor;

c) an actuator connected to the CPP GMR read/write head for moving the CPP GMR recording head across the magnetic recording disk;

d) a mechanism connected to the magnetic recording disk for moving the magnetic recording disk relative to the CPP GMR read/write head;

wherein the CPP magnetoresistive sensor comprises;

i) at least two magnetic layers; and

ii) at least one spacer layer disposed between the two magnetic layers, wherein the spacer layer comprises a heterogeneous material.

23. The disk drive of claim 22, wherein the heterogeneous material comprises conductive grains within a highly resistive matrix.