Patent ID: 8057926

Claim:
A perpendicular magnetic recording medium having at least a first magnetic recording layer and a second magnetic recording layer on a substrate in an order named, wherein the first magnetic recording layer and the second magnetic recording layer are a ferromagnetic layer having a granular structure in which non-magnetic grain boundary portions are formed between magnetic grains that have grown continuously in a columnar shape, wherein the grain boundary portions of the first magnetic recording layer and the second magnetic recording layer contain a plurality of kinds of oxides, wherein A<B where a content of all of the plurality of kinds of oxides contained in the first magnetic recording layer is defined by A mol %, and a content of all of the plurality of kinds of oxides contained in the second magnetic recording layer is defined by B mol % wherein the first layer is a composite oxide having at least one of Ti and Si and the second layer is a composite oxide having both Si and Ti, and wherein the content of the composite oxide in the second layer is in the range 10 mol %-12 mol % inclusive and the content of the composite oxide in first layer is in the range of at least 6 mol %.-8 mol %.