L10 FePt-oxide columnar perpendicular media with high coercivity and small grain size

Perpendicular L10 ordered FePt-oxide two-phase thin films with an average grain size of ∼7 nm were prepared by alternate sputtering of FePt and oxide at 475 deg. C. Very uniform and well-isolated columnar grains were obtained with coercivity as high as 7 kOe. It is found that the texture of thin films depends greatly on the thickness of FePt; SiO2 works better than MgO as the amorphous oxide, which provides for magnetic isolation of the FePt grains. The coercivity of the films rises with increasing grain size and thinner alternately sputtered single layers. Reducing the grain size to ∼2.9 nm produces granular grains with a coercivity of 3.5 kOe