Magnetic structure free layer stabilization
View Patent ↗A magnetic layered structure is presently disclosed comprising a pinned layer, a first anti-ferromagnetic layer that defines a magnetic orientation of the pinned layer, a free layer, a second anti-ferromagnetic layer that biases the free layer to a magnetic orientation approximately perpendicular to the magnetic orientation of the pinned layer, and a tuning layer positioned between and in contact with the second anti-ferromagnetic layer and the free layer that tunes free layer bias to a desired level.
1. A magnetic layered structure comprising:
a pinned layer;
a first anti-ferromagnetic layer that defines a magnetic orientation of the pinned layer;
a free layer;
a second anti-ferromagnetic layer and a third anti-ferromagnetic layer that bias the free layer to a magnetic orientation approximately perpendicular to the magnetic orientation of the pinned layer; and
a tuning layer that tunes free layer bias to a desired level and is separated from the free layer and positioned between the second anti-ferromagnetic layer and the third anti-ferromagnetic layer.
2. The magnetic layered structure of claim 1 , further comprising:
one or more side shields positioned adjacent the free layer along a major plane of the free layer.
3. The magnetic layered structure of claim 2 , wherein the side shields include a soft magnetic material.
4. The magnetic layered structure of claim 2 , wherein the side shields include a non-magnetic material.
5. The magnetic layered structure of claim 1 , further comprising:
two electrodes, each positioned on opposite sides of the layered structure, configured to conduct current through the layered structure along an axis approximately perpendicular to a major plane of the free layer.
6. The magnetic layered structure of claim 1 , further comprising:
a spacer layer that magnetically separates the pinned layer from the free layer.
7. The magnetic layered structure of claim 1 , further comprising:
a capping layer that protects the second anti-ferromagnetic layer from post deposition damage.
8. The magnetic layered structure of claim 1 , wherein the pinned layer, first anti-ferromagnetic layer, free layer, and second anti-ferromagnetic layer comprise a read element sensor.
9. The magnetic layered structure of claim 1 , wherein approximately perpendicular is perpendicular +/−15 degrees.
10. The magnetic layered structure of claim 1 , wherein the first and second anti-ferromagnetic layers comprise IrMn or PtMn and have a thickness greater than or equal to 30 Å and less than or equal to 250 Å.
11. The magnetic layered structure of claim 1 , wherein the free layer comprises a first free layer and a second free layer.
12. The magnetic layered structure of claim 1 , wherein the structure further comprises multiple spacer layers including at least one of soft magnetic or nonmagnetic material to increase pinning field strength.
13. The magnetic layered structure of claim 1 , wherein the tuning layer decouples the free layer and the second anti-ferromagnetic layer while reducing dispersion of a free layer magnetic moment.
14. A method of biasing a magnetic layered structure, comprising:
defining a magnetic orientation of a pinned layer using a first anti-ferromagnetic layer;
biasing a magnetic orientation of a free layer using a second anti-ferromagnetic layer and a third anti-ferromagnetic layer, wherein the defined magnetic orientation of the pinned layer is approximately perpendicular to the biased magnetic orientation of the free layer; and
tuning free layer bias to a desired level using a tuning layer that decouples the free layer and the second anti-ferromagnetic layer wherein the tuning layer is separated from the free layer and positioned between the second anti-ferromagnetic layer and the third anti-ferromagnetic layer.
15. The method of claim 14 , further comprising:
shielding the free layer from external electromagnetic and/or thermal interference using one or more side shields positioned adjacent the free layer along a major plane of the free layer.
16. The method of claim 14 , further comprising:
conducting current along an axis approximately perpendicular to a major plane of the free layer between two electrodes positioned on opposite sides of the first anti-ferromagnetic layer, pinned layer, free layer, and second anti-ferromagnetic layer.
17. The method of claim 14 , further comprising:
decoupling the free layer and the second anti-ferromagnetic layer while reducing dispersion of a free layer magnetic moment.
18. The method of claim 14 , further comprising:
decoupling the free layer and the second anti-ferromagnetic layer while reducing dispersion of a free layer magnetic moment.
19. A transducer for a magnetic disc drive comprising:
a reader, including
a pinned layer;
a first anti-ferromagnetic layer that defines a magnetic orientation of the pinned layer;
a free layer;
a second anti-ferromagnetic layer and a third anti-ferromagnetic layer that bias the free layer to a magnetic orientation approximately perpendicular to the magnetic orientation of the pinned layer; and
a tuning layer that tunes free layer bias to a desired level, wherein the tuning layer is separated from the free layer and positioned between the second anti-ferromagnetic layer and the third antiferromagnetic layer.
20. The transducer of claim 19 , wherein the reader further includes one or more side shields positioned adjacent the free layer along a major plane of the free layer that shields the free layer from external electromagnetic interference.
21. The transducer of claim 19 , wherein the reader further includes two electrodes, each positioned on opposite sides of the layered structure, configured to conduct current through the layered structure along an axis approximately perpendicular to a major plane of the free layer.