Patent ID: 7267896

Claim:
A magnetic recording medium comprising a non-magnetic support, at least one lower magnetic layer containing magnetic powder and a binder resin, which is formed on one side of the non-magnetic support with or without a non-magnetic primer layer interposed between the non-magnetic support and the lower magnetic layer, at least one non-magnetic intermediate layer containing non-magnetic powder and a binder resin, which is formed on the lower magnetic layer, at least one upper magnetic layer containing magnetic powder and a binder resin, which is formed on the non-magnetic intermediate layer, and a back layer which is formed on the other side of the non-magnetic support, wherein the magnetic powder contained in the uppermost magnetic layer of the upper magnetic layer is a magnetic powder which comprises iron and is substantially spherical or ellipsoidal particles with a number-average particle diameter of 5 to 50 nm and an average axial ratio of 1 to 2, each of said particles has a core portion and an outer layer portion, wherein said core portion contains an iron nitride phase in which a part of the iron is optionally substituted by another transition element, and wherein a rare earth element is present mainly in said outer layer portion; and that the total thickness of the magnetic recording medium is 6 μm or less.