Spin-torque oscillator with multilayer seed layer between the write pole and the free layer in a magnetic recording write head
A magnetic recording write head and system has a spin-torque oscillator (STO) located between the write head's write pole and trailing shield. The STO's ferromagnetic free layer is located near the write pole with a multilayer seed layer between the write pole and the free layer. The STO's nonmagnetic spacer layer is between the free layer and the STO's ferromagnetic polarizer. The polarizer may be the trailing shield of the write head, one or more separate polarizer layers, or combinations thereof. The STO electrical circuitry causes electron flow from the write pole to the trailing shield. The multilayer seed layer removes the spin polarization of electrons from the write pole, which enables electrons reflected from the polarizer layer to become spin polarized, which creates the spin transfer torque on the magnetization of the free layer. The multilayer seed layer includes a Mn or a Mn-alloy layer.
1. A magnetic recording drive, comprising:
a recording layer,
a write head moveable relative to the recording layer, the write head comprising:
a main pole;
a trailing shield;
a spin-torque oscillator (STO) coupled to the main pole and the trailing shield and having a surface facing the recording layer; the STO comprising:
a nonmagnetic electrically conductive seed layer on the main pole, the nonmagnetic electrically conductive seed layer comprising a short spin diffusion length layer, wherein the short spin diffusion length layer comprises Mn;
a polarizer layer; and
a ferromagnetic free layer between the polarizer layer and the trailing shield.
2. The magnetic recording drive of claim 1 , wherein the short spin diffusion length layer is a Mn layer.
3. The magnetic recording drive of claim 1 , wherein the short spin diffusion length layer is a Mn alloy layer of Mn and one or more of Ir, Pt, Ni, Fe, Pd, Rh, Cu, Ta, Cr, Ru, Hf and Nb.
4. The magnetic recording drive of claim 1 , wherein the short spin diffusion length layer is a Mn alloy layer or an IrMn alloy layer.
5. The magnetic recording drive of claim 1 , wherein the nonmagnetic electrically conductive seed layer further comprises a non-magnetic layer between the main pole and the short spin diffusion length layer.
6. The magnetic recording drive of claim 1 , wherein the nonmagnetic electrically conductive seed layer further comprises a non-magnetic layer between the short spin diffusion length layer and the ferromagnetic free layer.
7. The magnetic recording drive of claim 1 , wherein the polarizer layer comprises CoFe, NiFe, CoFeNi, CoMnGe, NiCo, NiFeCo, CoFeMnGe, CoMnSi, or CoFeSi.
8. The magnetic recording drive of claim 1 , wherein the STO further comprises a capping layer disposed on the polarizer layer.
9. The magnetic recording drive of claim 8 , wherein the capping layer comprises Ru, Ir, Ta, Ti or alloys thereof.
10. A magnetic recording write head, comprising:
a main pole,
a nonmagnetic electrically conductive seed means removing spin polarization from electrons flowing from the main pole and interfacing with a spin polarization layer of a spin torque oscillator device, wherein the nonmagnetic electrically conductive seed means comprises Mn;
a ferromagnetic free layer; and
a trailing shield over the spin torque oscillator device.
11. The magnetic recording write head of claim 10 , further comprising a polarizer layer between the nonmagnetic electrically conductive seed means and the ferromagnetic free layer.
12. The magnetic recording head of claim 11 , further comprising a spacer layer disposed between the polarizer layer and the ferromagnetic free layer.
13. The magnetic recording write head of claim 10 , further comprising a polarizer layer between the ferromagnetic free layer and the trailing shield.
14. The magnetic recording head of claim 13 , further comprising a spacer layer disposed between the polarizer layer and the ferromagnetic free layer.
15. The magnetic recording write head of claim 10 , without a polarizer layer.
16. The magnetic recording write head of claim 15 , further comprising a spacer layer disposed between the trailing shield and the ferromagnetic free layer.
17. A magnetic recording write head, comprising:
a main pole,
a nonmagnetic electrically conductive seed layer on the main pole, a nonmagnetic electrically conductive seed layer comprising a Mn layer or a Mn alloy layer of Mn and one or more of Ir, Pt, Ni, Fe, Pd, Rh, Cu, Ta, Cr, Ru, Hf and Nb;
a trailing shield;
a ferromagnetic free layer between the nonmagnetic electrically conductive seed layer and the trailing shield; and
two or more polarizers selected from the group consisting of a trailing shield polarizer layer, a polarizer layer between the free layer and the trailing shield, and a polarizer layer between nonmagnetic electrically conductive seed layer and the free layer.
18. The magnetic recording write head of claim 17 , further comprising a spacer layer disposed between the ferromagnetic free layer and the polarizer.
19. The magnetic recording write head of claim 18 , wherein the spacer layer is non-magnetic.
20. The magnetic recording write head of claim 18 , wherein the spacer layer comprises Cu, Au, or Ag.