Spin valve sensor having an antiparallel (AP) self-pinned layer structure comprising cobalt for high magnetostriction
View Patent ↗In one illustrative embodiment of the invention, a spin valve sensor of a magnetic head has a free layer structure; an antiparallel (AP) self-pinned layer structure; and a non-magnetic electrically conductive spacer layer in between the free layer structure and the AP self-pinned layer structure. The AP self-pinned layer structure includes a first AP pinned layer; a second AP pinned layer; an antiparallel coupling (APC) layer formed between the first and the second AP pinned layers. At least one of the first and the second AP pinned layers is made of cobalt having no iron content. The other AP pinned layer may be formed of cobalt, cobalt-iron, or other suitable material. The use of cobalt in the AP self-pinned layer structure increases its magnetostriction to increase the self-pinning effect. Preferably, the first AP pinned layer is cobalt-iron and the second AP pinned layer is cobalt which provides for both an increase in magnetostriction and magnetoresistive coefficient Δr/R of the sensor.
1. A spin valve sensor for a magnetic head, comprising:
a free layer structure;
an antiparallel (AP) self-pinned layer structure;
a non-magnetic electrically conductive spacer layer in between the free layer structure and the AP self-pinned layer structure;
the AP self-pinned layer structure being pinned by its magnetostriction and air bearing surface (ABS) stress without any antiferromagnetic (AFM) layer being utilized for pinning;
the AP self-pinned layer structure including:
a first AP pinned layer comprising a cobalt-iron layer;
a second AP pinned layer comprising a cobalt layer and including no iron content;
the second AP pinned layer being in closer proximity to the free layer structure than the first AP pinned layer; and
an antiparallel coupling (APC) layer formed between the first and the second AP pinned layers.
2. The spin valve sensor of claim 1 , wherein the second AP pinned layer comprising the cobalt layer consists of cobalt.
3. The spin valve sensor of claim 1 , wherein the magnetostriction which self-pins the AP self-pinned layer structure is increased from use of the cobalt layer.
4. The spin valve sensor of claim 1 , wherein a magnetostriction of the first and the second AP pinned layers and a magnetoresistive coefficient of the spin valve sensor are increased from use of the cobalt layer.
5. The spin valve sensor of claim 1 , further comprising:
a seed layer which includes a layer of platinum-manganese (PtMn) with a thickness less than 75 Angstroms.
6. A disk drive, comprising:
a housing;
a magnetic disk rotatably supported in the housing;
a magnetic head assembly;
a support mounted in the housing for supporting the magnetic head assembly so as to be in a transducing relationship with the magnetic disk;
a spindle motor for rotating the magnetic disk;
an actuator positioning means connected to the support for moving the magnetic head assembly to multiple positions with respect to said magnetic disk;
a processor connected to the magnetic head assembly, to the spindle motor, and to the actuator for exchanging signals with the magnetic head assembly for controlling movement of the magnetic disk and for controlling the position of the magnetic head assembly;
the magnetic head assembly including a read head; the read head including a spin valve sensor comprising:
a free layer structure;
an antiparallel (AP) self-pinned layer structure;
a non-magnetic electrically conductive spacer layer in between the free layer structure and the AP self-pinned layer structure;
the AP self-pinned layer structure being pinned by its magnetostriction and air bearing surface (ABS) stress without any antiferromagnetic (AFM) layer being utilized for pinning;
the AP self-pinned layer structure including:
a first AP pinned layer comprising a cobalt-iron layer;
a second AP pinned layer comprising a cobalt layer and including no iron content;
the second AP pinned layer being in closer proximity to the free layer structure than the first AP pinned layer; and
an antiparallel coupling (APC) layer formed between the first and the second AP pinned layer.
7. The disk drive of claim 6 , wherein the second AP pinned layer comprising the cobalt layer consists of cobalt.
8. The disk drive of claim 6 , wherein the free layer structure comprises a cobalt-iron layer.
9. The disk drive of claim 6 , wherein a magnetostriction which self-pins the AP self-pinned layer structure is increased from use of the cobalt layer.
10. The disk drive of claim 6 , wherein the spin valve sensor further comprises:
a seed layer which includes a layer of platinum-manganese (PtMn) with a thickness less than 75 Angstroms.
11. The disk drive of claim 6 , wherein the magnetostriction of the first and the second AP pinned layers and a magnetoresistive coefficient of the spin valve sensor are increased from use of the cobalt layer.
12. A method of making a spin valve sensor for a magnetic head, comprising:
forming a free layer structure and an antiparallel (AP) self-pinned layer structure which are separated by a non-magnetic electrically conductive spacer layer, the AP self-pinned layer structure being pinned by its magnetostriction and air bearing surface (ABS) stress without any antiferromagnetic (AFM) layer being utilized for pinning; and
forming the AP self-pinned layer structure with a first AP pinned layer comprising a cobalt-iron layer, a second AP pinned layer comprising a cobalt layer and including no iron content, and an antiparallel coupling (APC) layer between the first and the second AP pinned layers, the second AP pinned layer being in closer proximity to the free layer structure than the first AP pinned layer.
13. The method of claim 12 , wherein the second AP pinned layer being formed with the cobalt layer having no iron content and the first AP pinned layer structure being formed with cobalt-iron increases a magnetoresistive coefficient Δr/R of the spin valve sensor.
14. The method of claim 12 , wherein the second AP pinned layer being formed with the cobalt layer having no iron content increases the magnetostriction of the AP self-pinned layer structure for improved self-pinning.
15. The method of claim 12 , wherein the free layer structure is formed with cobalt-iron.