Topological insulator based spin torque oscillator reader
The present disclosure generally relates to a bismuth antimony (BiSb) based STO (spin torque oscillator) sensor. The STO sensor comprises a SOT device and a magnetic tunnel junction (MTJ) structure. By utilizing a BiSb layer within the SOT device, a larger spin Hall angle (SHA) can be achieved, thereby improving the efficiency and reliability of the STO sensor.
1. A sensor, comprising:
a seed layer;
a magnetic tunnel junction (MTJ) structure disposed over the seed layer;
a first buffer layer disposed over the MTJ structure;
a bismuth antimony (BiSb) layer disposed over the first buffer layer;
a second buffer layer disposed over the BiSb layer;
a capping layer disposed over the second buffer layer, wherein the seed layer, the MTJ structure, the first buffer layer, the BiSb layer, the second buffer layer, and the capping layer are disposed at a media facing surface (MFS); and
an antiferromagnetic (AFM) layer, wherein the AFM layer is adjacent to the MTJ structure.
2. The sensor of claim 1 , wherein the AFM layer is disposed at the MFS and in contact with the seed layer.
3. The sensor of claim 1 , wherein the AFM layer and a free layer of the MTJ structure are at least partially aligned in a direction perpendicular to the MFS.
4. The sensor of claim 1 , wherein the AFM layer and a free layer of the MTJ structure are not aligned in a direction perpendicular to the MFS.
5. The sensor of claim 1 , wherein the first buffer layer is disposed in contact with a free layer of the MTJ structure.
6. A magnetic recording head comprising the sensor of claim 1 .
7. A magnetic recording device, comprising:
a magnetic recording media;
the magnetic recording head of claim 6 ; and
a control unit configured to:
flow current through the bismuth antimony (BiSb) layer while reading data from the magnetic recording media; and
measure frequency of a precession of a free layer in the sensor, wherein the precession is responsive to a magnetic field generated by the magnetic recording media.
8. A sensor, comprising:
a seed layer;
a magnetic tunnel junction (MTJ) structure disposed over the seed layer, the MTJ structure comprising:
a pinning layer disposed on the seed layer;
an insulation layer disposed over the seed layer; and
a free layer disposed on the insulation layer;
a first buffer layer disposed over the MTJ structure;
a bismuth antimony (BiSb) layer disposed over the first buffer layer;
a second buffer layer disposed over the BiSb layer;
a capping layer disposed over the second buffer layer, wherein the seed layer, the MTJ structure, the first buffer layer, the BiSb layer, the second buffer layer, and the capping layer are disposed at a media facing surface (MFS); and
an antiferromagnetic (AFM) layer, wherein the AFM layer is adjacent to the MTJ structure and in contact with the seed layer.
9. The sensor of claim 8 , wherein the AFM layer is disposed at the MFS.
10. The sensor of claim 8 , wherein the AFM layer is recessed from the MFS.
11. The sensor of claim 8 , wherein the AFM layer and the free layer are at least partially aligned in a direction perpendicular to the MFS.
12. The sensor of claim 8 , wherein the AFM layer and the free layer are unaligned in a direction perpendicular to the MFS.
13. A magnetic recording head comprising the sensor of claim 8 .