Patent ID: 9406328
Filing Date: 2016-08-02
CPC Classification: G11B

Claim Text:
1. A perpendicular magnetic recording medium, comprising: a substrate; and a soft magnetic underlayer structure positioned above the substrate, wherein the soft magnetic underlayer structure comprises: wherein a difference between a magnetic flux density of the soft magnetic underlayer structure at 25° C. and a magnetic flux density of the soft underlayer structure at 85° C. is less than or equal to about 10% of the magnetic flux density of the soft magnetic underlayer structure at 25° C., wherein at least one of the soft underlayers comprises a soft magnetic alloy including Co and Fe, wherein an amount of Co in the soft magnetic alloy satisfies the condition: where Co_c represents the atomic percentage of Co in the soft magnetic alloy, Fe_c represents the atomic percentage of Fe in the soft magnetic alloy, and Bs(RT) represents the magnetic flux density of the soft underlayer structure in Teslas.