Patent ID: 8871368
Filing Date: 2014-10-28
Classification: G11B

Abstract:
1. A perpendicular magnetic recording medium, comprising in the following order: a base; a first magnetic recording layer having a granular structure in which a non-magnetic grain boundary portion is formed between crystal particles grown in a columnar shape; a second magnetic recording layer having a granular structure in which a non-magnetic grain boundary portion is formed between crystal particles grown in a columnar shape; a second split layer that is disposed on the second magnetic recording layer and that contains a Ru alloy as a main component and; a third magnetic recording layer having a granular structure in which a non-magnetic grain boundary portion is formed between crystal particles grown in a columnar shape; a first split layer that is disposed on the third magnetic recording layer and that contains a Ru alloy as a main component; and an auxiliary recording layer that contains Cr, that is disposed on the split layer and that is magnetically approximately continuous in an in-plane direction of a main surface of the base, wherein the first split layer is operative to reduce the migration of Cr from the auxiliary layer into the third magnetic layer upon anneal at 200 C or higher, as indicated by a reduced drop in coercivity (Oe) compared to an identical structure absent the first split layer.