Magnetic sensor having a high spin polarization reference layer
View Patent ↗A magnetic sensor configured to reside in proximity to a recording medium during use having a high spin polarization reference layer stack above AFM layers. The reference layer stack comprises a first boron-free ferromagnetic layer above the AFM coupling layer; a magnetic coupling layer on and in contact with the first boron-free ferromagnetic layer; a second ferromagnetic layer comprising boron deposited on and contact with the magnetic coupling layer; and a boron-free third ferromagnetic layer on and in contact the second ferromagnetic layer. A barrier layer is deposited on and in contact with the boron-free third ferromagnetic layer. In one aspect of the invention, the magnetic coupling layer may comprise at least one of Ta, Ti, or Hf. A process for providing the magnetic sensor is also provided.
1. A magnetic sensor configured to reside in proximity to a recording medium during use, the magnetic sensor comprising:
a magnetic top shield and a magnetic bottom shield;
a seed layer above the magnetic bottom shield;
a spacer above the seed layer;
an antiferromagnetic (AFM) layer above the spacer layer;
a pinned layer above the AFM layer;
an AFM coupling layer above the pinned layer,
a high spin polarization reference layer stack above the AFM coupling layer, comprising:
a first boron-free ferromagnetic layer above the AFM coupling layer;
a magnetic coupling layer on and in contact with the first boron-free ferromagnetic layer;
a second ferromagnetic layer comprising boron, the second ferromagnetic layer deposited on and contact with the magnetic coupling layer;
a boron-free third ferromagnetic layer on and in contact the second ferromagnetic layer;
a barrier layer deposited on and in contact with the boron-free third ferromagnetic layer;
a free layer above the barrier layer, and
a capping layer above the free layer.
2. The recording transducer of claim 1 wherein the magnetic coupling layer comprises a layer of elemental Ta.
3. The recording transducer of claim 1 wherein the magnetic coupling layer comprises a material selected from the group consisting of Ta, Ti, and Hf.
4. The recording transducer of claim 1 wherein the second ferromagnetic layer has a boron content between approximately 15 and 25 atomic percent.
5. The recording transducer of claim 1 wherein the first boron-free ferromagnetic layer consists essentially of CoFe.
6. The recording transducer of claim 5 wherein the first boron-free ferromagnetic layer comprises between approximately 8 and 15 atomic percent Fe.
7. The recording transducer of claim 1 wherein the first boron-free ferromagnetic layer has a thickness between 0.5 nanometers (nm) and 1.5 nm.
8. The recording transducer of claim 1 wherein the first magnetic coupling layer has a thickness less than 0.5 nm.
9. The recording transducer of claim 1 wherein the second ferromagnetic layer is an amorphous alloy comprising at least one of Co, Fe, and Ni.
10. The recording transducer of claim 1 wherein the second ferromagnetic layer comprises at least one of CoFeB, CoB, or CoFeNiB.
11. The recording transducer of claim 1 wherein second ferromagnetic layer has a thickness between 1.5 nm and 2.5 nm.
12. The recording transducer of claim 1 wherein the boron-free third ferromagnetic layer comprises a soft magnetic alloy of Co, Fe, or CoFe.
13. The recording transducer of claim 1 wherein the boron-free third ferromagnetic layer has a thickness between 0.3 and 0.7 nm.
14. A magnetic sensor configured to reside in proximity to a recording medium during use, the magnetic sensor comprising:
an antiferromagnetic (AFM) layer;
a pinned layer above the AFM layer;
an AFM coupling layer above the pinned layer;
a high spin polarization reference layer stack above the AFM coupling layer, comprising:
a first boron-free ferromagnetic layer above the AFM coupling layer, the first boron-free ferromagnetic layer comprising CoFe or a crystalline alloy of CoFe;
a magnetic coupling layer on and in contact with the first boron-free ferromagnetic layer, the magnetic coupling layer comprising at least one of Ta, Ti, or Hf;
a second ferromagnetic layer comprising boron and at least one of Co and Fe, the second ferromagnetic layer deposited on and contact with the magnetic coupling layer;
a boron-free third ferromagnetic layer on and in contact the second ferromagnetic layer, the third ferromagnetic layer comprising CoFe;
a barrier layer deposited on and in contact with the boron-free third ferromagnetic layer;
a free layer above the barrier layer, and
a capping layer above the free layer.
15. A disk drive comprising:
a slider including a magnetic sensor, the magnetic sensor configured to reside in proximity to a recording medium during use, the magnetic sensor comprising:
an antiferromagnetic (AFM) layer;
a pinned layer above the AFM layer;
an AFM coupling layer above the pinned layer;
a high spin polarization reference layer stack above the AFM coupling layer, wherein the reference layer stack comprises:
a first boron-free ferromagnetic layer above the AFM coupling layer, the first boron-free ferromagnetic layer comprising CoFe or a crystalline alloy of CoFe;
a magnetic coupling layer on and in contact with the first boron-free ferromagnetic layer, the magnetic coupling layer comprising at least one of Ta, Ti, or Hf;
a second ferromagnetic layer comprising boron and the second ferromagnetic layer comprising at least one of Co and Fe, the second ferromagnetic layer deposited on and contact with the magnetic coupling layer;
a boron-free third ferromagnetic layer on and in contact the second ferromagnetic layer, the third ferromagnetic layer comprising CoFe;
a barrier layer deposited on and in contact with the boron-free third ferromagnetic layer;
a free layer above the barrier layer, and
a capping layer above the free layer.
16. A method of providing a high spin polarization reference layer for a magnetic recording sensor, the method comprising:
providing an antiferromagnetic (AFM) layer;
providing a pinned layer above the AFM layer;
providing an AFM coupling layer above the pinned layer;
depositing a first boron-free ferromagnetic layer above the AFM coupling layer, the first boron-free ferromagnetic layer comprising CoFe or a crystalline alloy of CoFe;
depositing a magnetic coupling layer on and in contact with the first boron-free ferromagnetic layer, the magnetic coupling layer comprising at least one of Ta, Ti, or Hf;
depositing a second ferromagnetic layer comprising boron and at least one of Co and Fe, the second ferromagnetic layer deposited on and contact with the magnetic coupling layer;
after depositing the second ferromagnetic layer, exposing the second ferromagnetic layer to gaseous plasma;
depositing a boron-free third ferromagnetic layer comprising CoFe, or a soft magnetic alloy of Co, Fe, or CoFe, the third ferromagnetic layer on and in contact the second ferromagnetic layer;
depositing at least one barrier layer on and in contact with the as-deposited boron-free third ferromagnetic layer.
17. The recording transducer of claim 16 wherein the second ferromagnetic layer has a boron content between approximately 15 and 25 atomic percent.
18. The recording transducer of claim 16 wherein the magnetic coupling layer comprises between approximately 8 and 15 atomic percent Fe.
19. The recording transducer of claim 16 wherein the first boron-free ferromagnetic layer has a thickness between 0.5 nanometers (nm) and 1.5 nm.
20. The recording transducer of claim 16 wherein the magnetic coupling layer has a thickness less than 0.5 nm.