Patent ID: 7704613

Claim:
A magnetic recording medium comprising: a substrate; an underlayer film formed above the substrate; a magnetic film comprising a first magnetic layer, a first non-magnetic intermediate layer, a second magnetic layer, a third magnetic layer formed directly on the second magnetic layer, a second non-magnetic intermediate layer and a fourth magnetic layer stacked above the underlayer film; and a protective layer formed above the magnetic film; wherein: a product (Brt2) of residual magnetic flux density and film thickness of the second magnetic layer is smaller than a product (Brt3) of residual magnetic flux density and film thickness of the third magnetic layer; the second magnetic layer has a thickness larger than a thickness of the third magnetic layer; the second magnetic layer is coupled anti-ferromagnetically with the first magnetic layer by way of the first non-magnetic intermediate layer; the fourth magnetic layer is formed by way of the second non-magnetic intermediate layer above the third magnetic layer; and a product (Brt4) of residual magnetic flux density and film thickness of the fourth magnetic layer is from about 47% to 52% of a product (Brt_total) of residual magnetic flux density and film thickness of entire magnetic layers in a state of residual magnetization with an external magnetic field removed.