Patent ID: 7875372
Filing Date: 2011-01-25
Classification: C23C,G11B

Abstract:
1. A perpendicular magnetic recording medium comprising an adhesion layer, a soft magnetic layer, a granular magnetic layer, and a protective layer formed above a substrate, wherein the protective layer includes three diamond like carbon layers each of which contains carbon as a main component, and hydrogen, a first layer of the protective layer has a thickness of from 7.5 to 25% of a total thickness of the protective layer and has a hydrogen content of from 33 to 38%, a second layer of the protective layer formed over the first layer has a thickness of from 50 to 85% of the total thickness of the protective layer and exclusively further contains nitrogen within the protective layer, and a nitrogen content of the second layer is from 3 to 7%, and a third layer of the protective layer formed over the second layer has a thickness of from 7.5 to 25% of the total thickness of the protective layer and has a hydrogen content of 25% or less.