Anti-ferromagnetically coupled perpendicular magnetic recording media with oxide
View Patent ↗The present invention relates to perpendicular magnetic recording media with improved signal-to-medium noise ratio (“SMNR”) and thermal stability, which media include a pair of vertically spaced-apart perpendicular ferromagnetic layers which are anti-ferromagnetically coupled (“AFC”) across a non-magnetic spacer layer. The invention is of particular utility in the fabrication of data/information storage and retrieval media, e.g., hard disks, having ultra-high areal recording/storage densities.
1. An anti-ferromagnetically coupled (“AFC”) perpendicular magnetic recording medium, comprising:
a ferromagnetic stabilization layer with perpendicular anisotropy;
a non-magnetic spacer layer, wherein the non-magnetic spacer layer comprises Ru and an oxide selected from Si, Nb, Cr, W, Zr, or Ti; and
a perpendicularly anisotropic main recording layer, wherein said ferromagnetic stabilization layer and said perpendicularly anisotropic main recording layer are anti-ferromagnetically coupled across said non-magnetic spacer layer, and
each of the stabilization layer and the main recording layer comprise a ferromagnetic Co alloy, wherein the Co alloy comprises:
at least one element selected from Cr, Pt, Ta, B, Mo, Ru, Si, Ge, Nb, Fe, Ni and W, and
at least one oxide material selected from Al, Si, Ti, V, Mn, Co, Ni, Zn, Y, Zr, Nb, Mo, Hf and W.
2. The perpendicular magnetic recording medium as in claim 1 , wherein:
said non-magnetic spacer layer is from about 2 to about 20 Å thick, selected to maximize anti-ferromagnetic coupling between the stabilization layer and the main recording layer.
3. The perpendicular magnetic recording medium as in claim 2 , wherein: said non-magnetic spacer layer comprises Ru with 2 to 10 molar % of SiO 2 , or Ru with 2 to 7 molar % of Nb 2 O 5 , or Ru with 2 to 7 molar % of Cr 2 O 3 , or Ru with 2 to 9 molar % of W 0 3 , or Ru with 2 to 15 molar % of ZrO 2 , or Ru with 2 to 15 molar % of TiO 2 .
4. The perpendicular magnetic recording medium as in claim 2 , further comprising at least one ferromagnetic interface layer at an interface between said non-magnetic spacer layer and said main recording layer.
5. The perpendicular magnetic recording medium as in claim 2 , further comprising at least one ferromagnetic interface layer at an interface between said non-magnetic spacer layer and said stabilization layer.
6. The perpendicular magnetic recording medium as in claim 2 , further comprising at least one ferromagnetic interface layer at interfaces between said non-magnetic spacer layer and each of said main recording layer and said stabilization layer.
7. The perpendicular magnetic recording medium as in claim 1 , wherein:
said layer stack further includes at least one additional stacked pair of layers between said main recording layer and said non-magnetic spacer layer, comprising a perpendicularly anisotropic magnetic layer and a non-magnetic spacer layer, such that said layer stack comprises alternating magnetic layers and non-magnetic spacer layers, and magnetic energies of said magnetic layers and coupling energies between said magnetic layers are selected to provide anti-parallel alignment of magnetic moments of adjacent magnetic layers during data storage in said medium.
8. The perpendicular magnetic recording medium as in claim 7 , further comprising:
at least one ferromagnetic interface layer at at least one interface between said non-magnetic spacer layers and said main recording layers and said stabilization layer.
9. The perpendicular magnetic recording medium as in claim 1 , wherein:
said stabilization layer and said main recording layer comprises a CoPt or CoPtCr alloy with up to 12 molar % of Cr and Co oxide, or a CoPt or CoPtCr alloy with 2 to 10 molar % of SiO 2 and up to 10 molar % of Cr and Co oxide, or a CoPt or CoPtCr alloy with 2 to 7 molar % of Nb 2 O 5 and up to 10 molar % of Cr and Co oxide, or a CoPt or CoPtCr alloy with 2 to 9 molar % of WO 3 and up to 10 molar % of Cr and Co oxide or a CoPt or CoPtCr alloy with 2 to 15 molar % of ZrO 2 and up to 10 molar % of Cr and Co oxide, or a CoPt or CoPtCr alloy with 2 to 15 molar % of TiO 2 and up to 10 molar % of Cr and Co oxide.
10. The perpendicular magnetic recording medium as in claim 9 , wherein the up to 10 or 12 molar % of Cr and Co oxide include Cr 2 O 3 and CoO, respectively.
11. The perpendicular magnetic recording medium as in claim 1 , wherein:
said main recording layer is about 3 to about 300 Å thick.
12. A perpendicular magnetic recording medium, comprising:
a ferromagnetic stabilization layer with perpendicular anisotropy; and
a main recording layer with perpendicular anisotropy;
wherein each of the stabilization layer and the main recording layer comprise a Co alloy comprising at least one element selected from Cr, Pt, Ta, B, Mo, Ru, Si, Ge, Nb, Fe, Ni and W, and at least one oxide material selected from Al, Si, Ti, V, Mn, Co, Ni, Zn, Y, Zr, Nb, Mo, Hf and W; and
a non-magnetic spacer layer between the stabilization layer and the main recording layer, wherein the non-magnetic spacer layer comprises Ru and an oxide selected from Si, Nb, Cr, W, Zr or Ti; and
wherein the stabilization layer and main recording layer are anti-ferromagnetically coupled across the non-magnetic spacer layer.
13. The perpendicular magnetic recording medium of claim 12 , wherein the layer stack further comprises a ferromagnetic interface layer at an interface between said non-magnetic spacer layer and said main recording layer, wherein the at least one ferromagnetic interface layer has a saturation magnetization M s greater than 400 emu/cc, and wherein a concentration of Fe or Co in the ferromagnetic interface layer is higher near the interface with said non-magnetic spacer layer than at an interface with the main recording layer.
14. The perpendicular magnetic recording medium of claim 12 , wherein the non-magnetic spacer layer is from about 2 to about 20 Å thick, selected to maximize anti-ferromagnetic coupling between the stabilization layer and the main recording layer.
15. The perpendicular magnetic recording medium of claim 12 , wherein the non-magnetic spacer layer comprises Ru with 2 to 10 molar % of SiO 2 , or Ru with 2 to 7 molar % of Nb 2 O 5 , or Ru with 2 to 7 molar % of Cr 2 O 3 , or Ru with 2 to 9 molar % of W 0 3 , or Ru with 2 to 15 molar % of ZrO 2 , or Ru with 2 to 15 molar % of TiO 2 .
16. A perpendicular magnetic recording medium, comprising:
a stabilization layer with perpendicular anisotropy; and
a main recording layer with perpendicular anisotropy;
wherein each of the stabilization layer and the main recording layer comprise a Co alloy comprising:
at least one element selected from Cr, Pt, Ta, and B, and
at least one oxide; and
a non-magnetic spacer layer between the stabilization layer and the main recording layer, wherein the non-magnetic spacer layer comprises Ru and an oxide selected from Si, Nb, Cr, W, Zr, or Ti, and wherein the stabilization layer and main recording layer are anti-ferromagnetically coupled across the non-magnetic spacer layer.