Developing SmCo5 perpendicular magnetization thin films for magnetic recording media

Abstract

A series of our studies on sputter-deposited SmCo5 thin films exhibiting very high perpendicular magnetic anisotropy is reviewed. Introduction of a Cu underlayer is a key to imparting perpendicular magnetic anisotropy to SmCo5 thin films. Perpendicular magnetic anisotropy was enhanced by depositing the Sm-Co layer with the alternate lamination of Sm and Co sublayers and by using the Cu/Ti dual underlayer for producing a smooth film surface. As a result, under an optimized condition, the magnetic anisotropy constant was as large as 4.0 x 10 7 erg/cm 3 , which is greater by a factor of ten than that of material used for conventional magnetic recording media. Furthermore, we found that high perpendicular magnetic anisotropy was obtained even in very thin films and that the coercivity was controllable in a wide range when the films were prepared using an ultra-high vacuum sputtering system. Microstructural analysis suggested that the Cu-rich region in the initial growth stage of the Sm-Co layer played an important role in generating perpendicular magnetic anisotropy. In addition, we tested SmCo5 thin films for use in conventional and heat-assisted magnetic recording media.