Current perpendicular to plane magnetoresistive sensor having a shape enhanced pinned layer and an in stack bias structure
View Patent ↗A magnetoresistive sensor having an in stack bias structure and a pinned layer having shape enhanced anisotropy. The sensor may be a partial mill design wherein the track width of the sensor is defined by the width of the free layer and the pinned layers extend beyond the trackwidth of the sensor. The sensor has an active area defined by the stripe height of the free layer. The pinned layer extends beyond the stripe height defined by the free layer, thus providing the pinned layer with the shape enhanced anisotropy. The pinned layer structure can be pinned by exchange coupling with a layer of antiferromagnetic material (AFM) layer, with pinning robustness being improved by the shape enhanced anisotropy, or can be a self pinned structure which is pinned by a combination of magnetostriction, AP coupling and shape enhanced anisostropy.
1. A magnetoresistive sensor having an air bearing surface (ABS), the magnetoresistive sensor comprising:
a magnetic free layer, extending to a first stripe height distance measured from the ABS;
a magnetic pinned layer structure extending to a second stripe height distance that is larger than the first stripe height distance as measured from the ABS;
a first non-magnetic, electrically conductive spacer layer sandwiched between the free layer and the pinned layer structure; and
an in stack bias structure formed adjacent to the magnetic free layer opposite the first non-magnetic, electrically conductive spacer layer;
wherein the pinned layer structure includes first and second magnetic layers that are antiparallel coupled with on another across a non-magnetic, electrically conductive antiparallel coupling layer, and wherein one of the first and second magnetic layers in exchange coupled with a layer of antiferromagnetic material, and wherein both of the first and second magnetic layers extend beyond the first stripe height distance.
2. A sensor as in claim 1 , wherein the pinned layer has an extended portion that extends beyond the first stripe height distance SH 1 to the second stripe height distance SH 2 and wherein the pinned layer structure has a width in the extended portion that is substantially equal to a width of the free layer.
3. A sensor as in claim 1 , wherein the pinned layer has a width that is substantially equal to a width of the free layer.
4. A sensor as in claim 1 , wherein:
the free layer has a lateral width that defines a track width of the sensor;
the sensor has an active area between the ABS and SH 1 and an inactive area beyond SH 1 ; and
the pinned layer extends laterally beyond the trackwidth of the sensor.
5. A sensor as in claim 4 wherein the pinned layer has a width outside of the active area of the sensor (in a stripe height direction measured from the ABS) that is substantially equal to the trackwidth of the sensor.
6. A sensor as in claim 4 wherein the pinned layer extends laterally beyond the trackwidth of the sensor a distance at least twice the trackwidth of the sensor.
7. A sensor as in claim 4 wherein the pinned layer structure extends laterally indefinitely beyond the trackwidth of the sensor.
8. A sensor as in claim 4 wherein the pinned layer has a width beyond SH 1 that is larger than the trackwidth of the sensor.
9. A sensor as in claim 1 wherein the pinned layer structure comprises first and second magnetic layers (AP1 and AP2) and a non-magnetic, electrically conductive antiparallel coupling layer sandwiched between the AP1 and AP2 layers, the AP1 and AP2 layers being antiparallel coupled with one another, wherein the AP1 and AP2 layers are constructed of material having a positive magnetostricion, and wherein the magnetizations of the AP1 and AP2 layers are pinned without exchange coupling with a layer of antiferromagnetic material.
10. A sensor as in claim 1 wherein the in stack bias layer comprises:
a magnetic bias layer;
a second non-magnetic, electrically conductive spacer layer sandwiched between the bias layer and the free layer; and
a layer of antiferromagnetic material exchange coupled with the bias layer.
11. A sensor as in claim 10 wherein the bias layer has a magnetization that is pinned in a first direction parallel with the ABS, and the free layer has a magnetization that is biased in a second direction antiparallel with the first direction.
12. A sensor as in claim 10 wherein the bias layer has a magnetization that is pinned in a direction parallel with the ABS and the free layer is magnetostatically coupled with the bias layer.
13. A disk drive data storage system, comprising:
a housing;
a magnetic disk, rotatably mounted within the housing;
an actuator, pivotally mounted within the housing;
a slider connected with the actuator for movement adjacent to a surface of the magnetic disk;
a current perpendicular to plane CPP magnetoresisitive sensor connected with the slider and having an air bearing surface (ABS), the sensor comprising:
a magnetic free layer, extending to a first stripe height distance measured from the ABS;
a magnetic pinned layer structure extending to a second stripe height distance that is larger than the first stripe height distance as measured from the ABS;
a non-magnetic, layer sandwiched between the free layer and the pinned layer; and
an in stack bias structure formed adjacent to the magnetic free layer opposite the first non-magnetic, electrically conductive spacer layer;
wherein the pinned layer structure includes first and second magnetic layers that are antiparallel coupled with on another across a non-magnetic, electrically conductive antiparallel coupling layer, and wherein one of the first and second magnetic layers in exchange coupled with a layer of antiferromagnetic material, and wherein both of the first and second magnetic layers extend beyond the first stripe height distance.
14. A disk drive system as in claim 13 wherein the wherein the pinned layer has an extended portion that extends beyond the first stripe height distance SH 1 to the second stripe height distance SH 2 and wherein the pinned layer structure has a width in the extended portion that is substantially equal to a width of the free layer.
15. A disk drive system as in claim 13 wherein the pinned layer has a width that is substantially equal to a width of the free layer.
16. A disk drive system as in claim 13 , wherein:
the free layer has a lateral width that defines a track width of the sensor;
the sensor has an active area between the ABS and SH 1 and an inactive area beyond SH 1 ; and
the pinned layer extends laterally beyond the trackwidth of the sensor.
17. A disk drive system as in claim 16 , wherein the pinned layer has a width outside of the active area of the sensor that is substantially equal to the trackwidth of the sensor.
18. A disk drive system as in claim 16 , wherein the pinned layer extends laterally beyond the trackwidth of the sensor a distance at least twice the trackwidth of the sensor in the active area of the sensor.
19. A disk drive system as in claim 16 , wherein the pinned layer structure extends laterally indefinitely beyond the trackwidth of the sensor in the active area of the sensor.
20. A disk drive system as in claim 13 wherein the non-magnetic layer sandwiched between the free layer and the pinned layer is an electrically conductive spacer layer and the sensor is a current perpendicular to plane (CPP) giant magnetoresistive (GMR) sensor.
21. A disk drive system as in claim 13 wherein the non-magnetic layer sandwiched between the free layer and the pinned layer is an electrically insulating barrier layer and the sensor is a tunnel valve sensor.