Patent ID: 8309239

Claim:
A perpendicular magnetic recording medium comprising: a substrate; a magnetic recording layer on said substrate, and a medium-protecting layer on the magnetic recording layer, wherein the magnetic recording layer is a ferromagnetic layer of a granular structure having grain boundaries formed by a non-magnetic material among crystalline particles grown in a columnar shape and containing at least cobalt (Co); the medium protecting layer has a thickness in the range between 1.0 nm and less than 3.0 nm; and the medium-protecting layer is composed of a coating that includes carbon as a main component and nitrogen contained in a surface layer at a number ratio (N/C) of nitrogen (N) atoms and carbon (C) atoms of 0.090 to 0.150, and in a spectrum removed fluorescence from a Raman spectrum in wavenumbers of 900 to 1800 cm −1 obtained by exciting the medium-protecting layer with argon ion laser light having a 514.5 nm wavelength, a peak ratio Dh/Gh when a D peak Dh appearing near 1350 cm −1 and a G peak Gh appearing near 1520 cm −1 are waveform-separated by a Gaussian function is no less than 0.075 to less than 0.95.