Magnetic recording media having enhanced coupling between magnetic layers

A method of forming a magnetic recording medium having thermal stability, comprising steps of:

• (a) forming a layer stack overlying at least one surface of a non-magnetic substrate, said layer stack including at least one layer pair composed of first and second superposed, spaced-apart ferromagnetic layers;
• and
• (b) providing a magnetic coupling structure between said at least one pair of first and second ferromagnetic layers, said magnetic coupling structure comprising a non-magnetic spacer layer and at least one ferromagnetic interface layer at at least one interface between said non-magnetic spacer layer and said first and second ferromagnetic layers;
• wherein said non-magnetic spacer layer comprises an about 6 to about 10 Å thick layer of Ru or a Ru-based alloy and said at least one ferromagnetic interface layer comprises an about 1 monolayer thick to an about 40 Å thick layer of a cobalt alloy, wherein the concentration of Co in said alloy varies across the thickness of the interface layer from higher near the interface with the spacer layer to low nearer an interface with a ferromagnetic layer.