Patent ID: 7074508

Claim:
A magnetic recording medium comprising: a base structure; and a synthetic ferrimagnetic structure, disposed on said base structure, and forming a recording layer, said synthetic ferrimagnetic structure including at least a bottom magnetic layer and a top magnetic layer which are antiferromagnetically coupled via a nonmagnetic spacer layer, wherein said bottom magnetic layer is made of a superparamagnetic layer, satisfying KuV/k B T<25, where Ku is an anisotropy constant, V is a volume, T is a temperature of the superparamagnetic layer, and k B is Boltzmann's constant, and said top magnetic layer is made of a ferromagnetic material, and magnetic moment orientations of said bottom and top magnetic layers are antiparallel at a remanent state where an external applied magnetic field is zero, wherein said bottom magnetic layer is located nearest said base structure and is superparamagnetic above 273 K.