Perpendicular magnetic recording media with magnetic anisotropy gradient and local exchange coupling

摘要

A perpendicular magnetic recording medium adapted for high recording density and high data recording rate comprises a non-magnetic substrate having at least one surface with a layer stack formed thereon, the layer stack including a perpendicular recording layer containing a plurality of columnar-shaped magnetic grains extending perpendicularly to the substrate surface for a length, with a first end distal the surface and a second end proximal the surface, wherein each of the magnetic grains has: (1) a gradient of perpendicular magnetic anisotropy field Hk extending along its length between the first end and second ends; and (2) predetermined local exchange coupling strengths along the length.

主权项

1. A stack, comprising:
a substrate having at least one surface; and a layer stack on the surface of said substrate, the layer stack including a perpendicular recording layer comprising a plurality of columnar-shaped magnetic grains extending perpendicularly between opposing surfaces of the recording layer, each columnar-shaped magnetic grain comprising a plurality of sub-layers including: a first sub-layer having a first magnetic material, a thickness δ1, and a first magnetic anisotropy field Hk1; a second sub-layer adjacent to the first sub-layer, the second sub-layer having a second magnetic material, a thickness δ2, and a second magnetic anisotropy field Hk2; and a third sub-layer adjacent to the second sub-layer and having a third magnetic material, a thickness δ3, and a third magnetic anisotropy field Hk3, wherein Hk1 is between 8,000 and 20,000 Oe, Hk3 is between 1,000 and 9,000 Oe, wherein the total thickness of δ2+δ3 of the second and third sub-layers is less than the local exchange coupling distances of the second and third magnetic materials.