Patent ID: 7488545

Claim:
A perpendicular magnetic recording medium having regions magnetized in one of two remanent magnetic states and comprising: a substrate; a first recording layer on the substrate comprising a first ferromagnetic layer having an out-of-plane easy axis of magnetization, a second ferromagnetic layer having an out-of-plane easy axis of magnetization, and a Co-containing coupling layer on the first ferromagnetic layer and between the first ferromagnetic layer and the second ferromagnetic layer for ferromagnetic coupling of the first ferromagnetic layer with the second ferromagnetic layer, the ferromagnetically-coupled first and second ferromagnetic layers of the first recording layer having parallel magnetizations in the remanent magnetic states and the first ferromagnetic layer of the first recording layer having an anisotropy field greater than the anisotropy field of the second ferromagnetic layer of the first recording layer; a second recording layer comprising a first ferromagnetic layer having an out-of-plane easy axis of magnetization, a second ferromagnetic layer having an out-of-plane easy axis of magnetization, and a Co-containing coupling layer on the first ferromagnetic layer and between the first ferromagnetic layer and the second ferromagnetic layer for ferromagnetic coupling of the first ferromagnetic layer with the second ferromagnetic layer, the ferromagnetically-coupled first and second ferromagnetic layers of the second recording layer having parallel magnetizations in the remanent magnetic states and the first ferromagnetic layer of the second recording layer having an anisotropy field greater than the anisotropy field of the second ferromagnetic layer of the second recording layer and greater than the anisotropy field of the first ferromagnetic layer of the first recording layer; and a non-ferromagnetic spacer layer on the first recording layer and between the first recording layer and the second recording layer for magnetically decoupling the first and second recording layers, the first and second recording layers having parallel magnetizations in the remanent magnetic states.