Magnetoresistance element with improved response to magnetic fields
A magnetoresistance element has a pinning arrangement with two antiferromagnetic pinning layers, two pinned layers, and a free layer. A spacer layer between one of the two antiferromagnetic pinning layers and the free layer has a material selected to allow a controllable partial pinning by the one of the two antiferromagnetic pinning layers.
1. A magnetoresistance element deposited upon a substrate, comprising:
a stack of layers deposited upon the substrate, the stack of layers comprising:
a first antiferromagnetic pinning layer disposed over the substrate;
a second antiferromagnetic pinning layer disposed over the substrate;
a first synthetic antiferromagnet (SAF) structure disposed proximate to the first antiferromagnetic pinning layer;
a second synthetic antiferromagnet (SAF) structure disposed proximate to the second antiferromagnetic pinning layer, wherein the first and second synthetic antiferromagnet (SAF) structures are disposed between the first and second antiferromagnetic pinning layers, wherein the first and second antiferromagnetic pinning layers have different thicknesses, wherein the first and second antiferromagnetic layers are comprised of the same material, and wherein magnetic field directions in the first and second antiferromagnetic layers are annealed to have first and second directions, respectively, parallel to first and second lines, respectively, wherein the first and second lines are not parallel to each other; and
a free layer structure disposed between the first and second synthetic antiferromagnet (SAF) structures, the free layer structure comprising first and second free layers comprised of different respective materials.
2. The magnetoresistance element of claim 1 , wherein the first and second antiferromagnetic pinning layers are both comprised of PtMn.
3. The magnetoresistance element of claim 2 , wherein a thickness of the first antiferromagnetic pinning layer is in a first range of five to fifteen nanometers and the second antiferromagnetic pinning layer is a second range of fifteen to thirty nanometers.
4. The magnetoresistance element of claim 2 , wherein the magnetoresistance element has a yoke shape.
5. The magnetoresistance element of claim 4 , wherein a length (L) of the yoke shape and a length (d) of lateral arms of the yoke shape are each at least three times a width (w) of the yoke shape, and the width (w) of the yoke shape is between about one um and about twenty μm, wherein the length (L) is a longest dimension of the yoke shape.
6. The magnetoresistance element of claim 2 , wherein the magnetoresistance element comprises a spin valve.
7. The magnetoresistance element of claim 2 , wherein the magnetoresistance element comprises a GMR sensing element.
8. The magnetoresistance element of claim 2 , wherein the magnetoresistance element comprises a TMR sensing element.
9. The magnetoresistance element of claim 1 , wherein one of the first or second free layers is comprised of NiFe.
10. The magnetoresistance element of claim 1 , wherein one of the first or second free consists of NiFe.
11. The magnetoresistance element of claim 1 , wherein the first and second synthetic antiferromagnet (SAF) structures do not include the free layer structure.
12. The magnetoresistance element of claim 1 , wherein the first and second free layers have the same magnetic direction.
13. The magnetoresistance element of claim 1 , wherein the stack of layers further comprises:
a first nonmagnetic spacer layer disposed between the first synthetic antiferromagnet (SAF) structure and the free layer structure; and
a second nonmagnetic spacer layer disposed between the second synthetic antiferromagnet (SAF) structure and the free layer structure.
14. The magnetoresistance element of claim 1 , wherein one of the first or second free layers is comprised of a binary alloy.
15. A method of fabricating a magnetoresistance element, comprising:
depositing the magnetoresistance element in a stack of layers upon a substrate, the stack of layers comprising:
a first antiferromagnetic pinning layer disposed over the substrate;
a second antiferromagnetic pinning layer disposed over the substrate;
a first synthetic antiferromagnet (SAF) structure disposed proximate to the first antiferromagnetic pinning layer;
a second synthetic antiferromagnet (SAF) structure disposed proximate to the second antiferromagnetic pinning layer, wherein the first and second synthetic antiferromagnet (SAF) structures are disposed between the first and second antiferromagnetic pinning layers, wherein the first and second antiferromagnetic pinning layers have different thicknesses, wherein the first and second antiferromagnetic layers are comprised of the same material; and
a free layer structure disposed between the first and second synthetic antiferromagnet (SAF) structures, the free layer structure comprising first and second free layers comprised of different respective materials, the method further comprising:
annealing magnetic field directions in the first and second antiferromagnetic layers to have first and second directions, respectively, parallel to first and second lines, respectively, wherein the first and second lines are not parallel to each other.
16. The method of claim 15 , wherein the first and second antiferromagnetic pinning layers are both comprised of PtMn.
17. The method of claim 16 , wherein a thickness of the first antiferromagnetic pinning layer is in a first range of five to fifteen nanometers and the second antiferromagnetic pinning layer is a second range of fifteen to thirty nanometers.
18. The method of claim 16 , wherein the magnetoresistance element has a yoke shape.
19. The method of claim 18 , wherein a length (L) of the yoke shape and a length (d) of lateral arms of the yoke shape are each at least three times a width (w) of the yoke shape, and the width (w of the yoke shape is between about one μm and about twenty μm, wherein the length (L) is a longest dimension of the yoke shape.
20. The method of claim 16 , wherein the magnetoresistance element comprises a spin valve.
21. The method of claim 16 , wherein the magnetoresistance element comprises a GMR sensing element.
22. The method of claim 16 , wherein the magnetoresistance element comprises a TMR sensing element.
23. The method of claim 15 , wherein one of the first or second free layers is comprised of NiFe.
24. The method of claim 15 , wherein one of the first or second free layers consists of NiFe.
25. The method of claim 15 , wherein the first and second synthetic antiferromagnet (SAF) structures do not include the free layer structure.
26. The method of claim 15 , wherein the first and second free layers have the same magnetic direction.
27. The method of claim 15 , wherein the stack of layers further comprises:
a first nonmagnetic spacer layer disposed between the first synthetic antiferromagnet (SAF) structure and the free layer structure; and
a second nonmagnetic spacer layer disposed between the second synthetic antiferromagnet (SAF) structure and the free layer structure.
28. The method of claim 15 , Wherein one of the first or second free layers is comprised of a binary alloy.