Patent ID: 9640213
Date: 2017-05-02
CPC Classifications: G11B

Claim:
1. A perpendicular magnetic recording medium comprising: a nonmagnetic substrate; a perpendicular magnetic layer provided above the nonmagnetic substrate; and a protection layer provided on the perpendicular magnetic layer, wherein the perpendicular magnetic layer has a hexagonal close packed structure, and includes a plurality of stacked layers having a (0002) crystal plane oriented parallel to a surface of the nonmagnetic substrate, wherein an uppermost layer, amongst the plurality of stacked layers of the perpendicular magnetic layer, has a non-granular structure and includes polycrystal grains but does not include an oxide, nitride or carbide isolating the polycrystal grains, wherein the polycrystal grains are selected from a group consisting of a CoCr-base alloy, a CoPt-base alloy, a CoCrPt-base alloy, and a CoPtCr-base alloy, wherein the protection layer makes contact with the uppermost layer of the perpendicular magnetic layer, and includes a single graphene layer or a graphene stack, and an amorphous carbon layer, wherein the single graphene layer or the graphene stack is bonded in parallel to a (0002) crystal plane of the polycrystal grains, and wherein the graphene stack includes two or more and ten or less graphene layers that are stacked.