Perpendicular magnetic recording medium and method of manufacturing the same

Abstract

A vertical magnetic recording disc ( 100 ) includes a base ( 10 ), a magnetic recording layer ( 22 ), and a medium protection layer ( 26 ). The magnetic recording layer ( 22 ) is a ferromagnetic layer having a granular structure where a granular portion is formed. The medium protection layer ( 26 ) contains nitrogen (N) atoms and carbon (C) atoms with a number ratio (N/C) in a range from 0.050 to 0.150. In a Raman spectrum obtained by exciting the medium protection layer ( 26 ) by argon ion laser light of wavelength 514.5 nm, from which a fluorescence is removed, the peak ratio Dh/Gh is in a range from 0.70 to 0.95, when a D peak Dh appearing in the vicinity of 1350 cm −1 is separated from G peak Gh appearing in the vicinity of 1520 cm −1 by the Gauss function.

1 - 5 . (canceled) 
     
     
         6 . A method of manufacturing a perpendicular magnetic recording medium including a magnetic recording layer on a substrate, and a medium-protecting layer composed of a coating including carbon as a main component on the magnetic recording layer, comprising: forming 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), as the magnetic recording layer; heating the perpendicular magnetic recording medium such that in a spectrum removed fluorescence from a Raman spectrum of a medium-protecting layer formed later in wavenumbers of 900 to 1800 cm.sup.−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.sup.−1 and a G peak Gh appearing near 1520 cm.sup.−1 are waveform-separated by a Gaussian function is 0.70 to 0.95; forming the medium-protecting layer by a CVD method; and exposing the medium-protecting layer with nitrogen such that the number ratio (N/C) of nitrogen (N) atoms and carbon (C) atoms is 0.050 to 0.150. 
     
     
         7 . The method of manufacturing the perpendicular magnetic recording medium according to  claim 6 , further comprising: forming a soft magnetic layer of an antiferromagnetic exchange coupling (AFC) structure containing 30 to 70 at % iron (Fe) before the formation of the magnetic recording layer. 
     
     
         8 . The method of manufacturing the perpendicular magnetic recording medium according to  claim 7 , wherein the soft magnetic layer has an exchange coupling magnetic field Hex of 40 O e or more. 
     
     
         9 . The method of manufacturing the perpendicular magnetic recording medium according to  claim 6 , further comprising: forming a capped layer of a granular structure after the formation of the magnetic recording layer. 
     
     
         10 . The method of manufacturing the perpendicular magnetic recording medium according to  claim 9 , wherein the capped layer has a composition of CoCrPtB. 
     
     
         11 . The method of manufacturing the perpendicular magnetic recording medium according to  claim 6 , wherein the heating is performed at a temperature of 157 to 204.degree. C. 
     
     
         12 . The method of manufacturing the perpendicular magnetic recording medium according to  claim 6 , further comprising: exposing to a nitrogen atmosphere at a flow rate of 100 to 350 sccm so as to surface-treat the medium-protecting layer after forming the medium-protecting layer. 
     
     
         13 . The method of manufacturing the perpendicular magnetic recording medium according to  claim 6 , further comprising: forming a lubrication layer containing a perfluoro polyether compound having a hydroxyl group in an end group.