Scissor unidirectional biasing with hard bias stabilized soft bias
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.
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,
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.
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 , further comprising a lower shield positioned below at least the scissor sensor stack in a thickness direction, the lower shield being electrically isolated from the hard 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 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.
6. 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.
7. The apparatus as recited in claim 6 , 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.
8. 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.
9. The apparatus as recited in claim 8 , 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.
10. 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.
11. 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.
12. 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,
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 a lower shield positioned therebelow.
13. A magnetic data storage system, comprising:
at least one magnetic head comprising the apparatus as recited in claim 12 ;
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. The apparatus as recited in claim 12 , further comprising a side shield positioned on one or more sides of the scissor sensor stack in a track width direction.
15. The apparatus as recited in claim 12 , 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.
16. 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,
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.
17. A magnetic data storage system, comprising:
at least one magnetic head comprising the apparatus as recited in claim 16 ;
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.
18. The apparatus as recited in claim 16 , further comprising a side shield positioned on one or more sides of the scissor sensor stack in a track width direction.
19. 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.
20. The apparatus as recited in claim 19 , 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.