Magnetic recording medium with nitride segregant, method for manufacturing same and magnetic recording and reproducing apparatus

A method for manufacturing a magnetic recording medium including a non-magnetic substrate, a soft magnetic underlayer, an orientation control layer, a perpendicular magnetic layer, and a protective layer arranged in this order, the method comprising:

• forming a first magnetic layer over the orientation control layer as part of the perpendicular magnetic layer by sputtering such that the first magnetic layer has a granular structure that contains a magnetic grain and that contains an oxide in a non-magnetic grain boundary;
• forming a second magnetic layer containing a magnetic grain at a location farthest from the orientation control layer in the perpendicular magnetic layer by sputtering, the second magnetic layer containing a non-magnetic segregant;
• and
• nitriding part of an element contained in the magnetic grain such that a grain boundary is formed and thereby the second magnetic layer has a granular structure by performing a nitriding treatment on the second magnetic layer having the non-magnetic structure,
• wherein the magnetic grains are CoPt based magnetic gins and the oxide content in the first magnetic layer is from 3 to 18 mol %.

A magnetic recording and reproducing apparatus, comprising:

• a recording medium including:
• a non-magnetic substrate;
• a soft magnetic underlayer provided over the non-magnetic substrate;
• an orientation control layer provided over the soft magnetic underlayer;
• a perpendicular magnetic layer provided over the orientation control layer;
• a protective layer over the perpendicular magnetic layer;
• a first magnetic layer provided in the perpendicular magnetic layer and having a granular structure that contains a magnetic grain and that contains an oxide in a non-magnetic grain boundary, and
• a second magnetic layer that contains a magnetic grain and is provided farthest from the non-magnetic substrate in the perpendicular magnetic layer, the second magnetic layer containing a non-magnetic segregant,
• wherein the second magnetic layer has a granular structure that contains a nitride of an element contained in the magnetic grain in a grain boundary,
• wherein the second magnetic layer is the farthest perpendicular magnetic layer underneath the protective layer, from the non-magnetic substrate, and
• wherein the magnetic grains are CoPt based magnetic grains and the oxide content in the first magnetic layer is from 3 to 18 mol %;
• and
• a magnetic head configured to record information in the recording medium and to reproduce the recorded information from the magnetic recording medium.