Patent ID: 7338725

Claim:
A magnetic recording medium comprising a non-magnetic substrate; a plurality of underlayers disposed on the non-magnetic substrate; a lower magnetic layer formed on an underlayer; a non-magnetic intermediate layer disposed on the lower magnetic layer; and an upper magnetic layer containing Co as a main component disposed on the non-magnetic intermediate layer and coupled antiferromagnetically with the lower magnetic layer, wherein at least one of the underlayers contains Cr as a main component and between 2 atomic percent (at %) and 12 atomic percent (at %) of B, wherein the lower magnetic layer has Co as a main component, and contains between 10 atomic percent (at %) and 16 atomic percent (at %) of Cr and the quantity C 1 /t 1 is between 3.6 and 6.2 where C l is a atomic percent (at %) of Cr contained in the lower magnetic layer and t l is a film thickness of the lower magnetic layer expressed in nm.