SCISSOR UNIDIRECTIONAL BIASING WITH HARD BIAS STABILIZED SOFT BIAS

• US 20160055866A1
• Filed: 08/20/2014
• Published: 02/25/2016
• Est. Priority Date: 08/20/2014
• Status: Active Grant

• Current Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Original Assignee: HGST Netherlands B.V. (Western Digital Corporation)
• Inventors: Le, Quang, Seagle, David J.
• Granted Patent: US 9,406,320 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 5/112 Manufacture of shielding device
• CPC Class Codes: G11B 5/315 Shield layers on both sides of the main pole, e.g. in perpendicular magnetic heads
• CPC Class Codes: G11B 5/39 using magneto-resistive devices or effects
• CPC Class Codes: G11B 5/3932 Magnetic biasing films

Abstract

In one embodiment, an apparatus includes a scissor sensor stack, a soft bias layer positioned behind the scissor sensor stack in an element height direction, the soft bias layer including a soft magnetic material, and a hard bias layer, at least a portion thereof being positioned behind the soft bias layer in the element height direction, the hard bias layer including a hard magnetic material having an initialization magnetization that is perpendicular to a media-facing surface of the apparatus to provide unidirectional anisotropy to the soft bias layer, wherein the scissor sensor stack includes a first free layer, a second free layer positioned above the first free layer, and a barrier layer positioned between the first free layer and the second free layer. Other apparatuses and methods for forming such apparatuses are described in more embodiments.

Claims

1. An apparatus, comprising:

a scissor sensor stack, comprising;

a first free layer;

a second free layer positioned above the first free layer; and

a barrier layer positioned between the first free layer and the second free layer;

a soft bias layer positioned behind the scissor sensor stack in an element height direction, the soft bias layer comprising a soft magnetic material; and

a hard bias layer, at least a portion thereof being positioned behind the soft bias layer in the element height direction, the hard bias layer comprising a hard magnetic material having an initialization magnetization that is perpendicular to a media-facing surface of the apparatus to provide unidirectional anisotropy to the soft bias layer.

2. The apparatus as recited in claim 1, wherein the scissor sensor stack further comprises a cap layer positioned above the second free layer.

3. The apparatus as recited in claim 1, wherein at least one portion of an upper surface of the hard bias layer is positioned closer to the media-facing surface of the apparatus than any portion of a lower surface of the hard bias layer, and wherein at least one portion of a lower surface of the soft bias layer is positioned farther from the media-facing surface of the apparatus than any portion of an upper surface of the soft bias layer.

4. The apparatus as recited in claim 1, wherein at least a portion of the hard bias layer is in direct contact with a back edge of the soft bias layer.

5. The apparatus as recited in claim 4, wherein a portion of the soft bias layer extends below the hard bias layer in the element height direction and is configured to electrically isolate the hard bias layer from a lower shield positioned therebelow.

6. The apparatus as recited in claim 1, further comprising an upper shield positioned above the scissor sensor stack, the upper shield being electrically coupled to and exchange isolated from the hard bias layer.

7. The apparatus as recited in claim 1, further comprising an insulating layer positioned between the soft bias layer and the hard bias layer, the insulating layer being configured to electrically isolate the soft bias layer from the hard bias layer.

8. The apparatus as recited in claim 7, wherein the insulating layer is further positioned below the hard bias layer and is configured to electrically isolate the hard bias layer from a lower shield positioned therebelow.

9. The apparatus as recited in claim 1, wherein the soft bias layer has a length in the element height direction which is at least twice a width in a track width direction to form shape anisotropy perpendicular to the media-facing surface of the apparatus.

10. The apparatus as recited in claim 9, wherein the scissor sensor stack has a width in the track width direction that is substantially equal to the width of the soft bias layer in the track width direction.

11. The apparatus as recited in claim 1, further comprising a side shield positioned on one or more sides of the scissor sensor stack in a track width direction.

12. The apparatus as recited in claim 1, wherein at least a portion of the hard bias layer extends beyond sides of the scissor sensor stack and the soft bias layer in a track width direction.

13. A magnetic data storage system, comprising:

at least one magnetic head comprising the apparatus as recited in claim 1;

a magnetic medium;

a drive mechanism for passing the magnetic medium over the at least one magnetic head; and

a controller electrically coupled to the at least one magnetic head for controlling operation of the at least one magnetic head.

14. A method for forming a sensor, the method comprising:

forming a first free layer;

forming a barrier layer above the first free layer;

forming a second free layer above the barrier layer, wherein the first free layer, the barrier layer, and the second free layer together form a scissor sensor stack;

forming a soft bias layer behind the scissor sensor stack in an element height direction, the soft bias layer comprising a soft magnetic material; and

forming a hard bias layer, at least a portion thereof being positioned behind the soft bias layer in the element height direction, the hard bias layer comprising a hard magnetic material having an initialization magnetization that is perpendicular to a media-facing surface of the sensor to provide unidirectional anisotropy to the soft bias layer.

15. The method as recited in claim 14, further comprising:

forming an upper shield above the scissor sensor stack, the upper shield being electrically coupled to and exchange isolated from the hard bias layer; and

forming a lower shield below the sensor stack, the lower shield being electrically isolated from the hard bias layer,

wherein at least one portion of an upper surface of the hard bias layer is positioned closer to the media-facing surface of the sensor than any portion of a lower surface of the hard bias layer, and

wherein at least one portion of a lower surface of the soft bias layer is positioned farther from the media-facing surface of the sensor than any portion of an upper surface of the soft bias layer.

16. The method as recited in claim 15, wherein at least a portion of the hard bias layer is in direct contact with a back edge of the soft bias layer, and wherein a portion of the soft bias layer extends below the hard bias layer in the element height direction and is configured to electrically isolate the hard bias layer from the lower shield.

17. The method as recited in claim 15, further comprising forming an insulating layer between the soft bias layer and the hard bias layer and between the hard bias layer and the lower shield, the insulating layer being configured to electrically isolate the soft bias layer from the hard bias layer and the hard bias layer from the lower shield.

18. The method as recited in claim 14, wherein the soft bias layer has a length in the element height direction which is at least twice a width in a track width direction to form shape anisotropy perpendicular to the media-facing surface of the sensor, and wherein the scissor sensor stack has a width in the track width direction that is substantially equal to the width of the soft bias layer in the track width direction.

19. The method as recited in claim 14, further comprising forming a side shield one or more sides of the scissor sensor stack in a track width direction.

20. The method as recited in claim 14, wherein at least a portion of the hard bias layer extends beyond sides of the scissor sensor stack and the soft bias layer in a track width direction.