Patent ID: 7701667
Filing Date: 2010-04-20
Classification: G11B

Abstract:
1. A perpendicular magnetic recording medium comprising a soft magnetic layer, an intermediate layer made from ruthenium or ruthenium alloy, a first recording layer, a second recording layer, and a protective layer formed in sequence on a substrate, characterized in that the first recording layer and the second recording layer contain cobalt as the main material and possess a granular structure including chromium and oxygen, the saturation magnetization of the first recording layer is lower than the saturation magnetization of the second recording layer, and when the saturation magnetization of the first recording layer is set as Ms1(emu per cubic centimeter), and the saturation magnetization of the second recording layer is set as Ms2 (emu per cubic centimeter), and the first recording layer film thickness is set to t1(nm), then (Ms2−Ms1)×t1 will be larger than approximately 0 (memu per square centimeter) and smaller than approximately 0.15 (memu per square centimeter).