CrMn underlayers for CoCrPt thin film media

An improved CoCrPt thin film medium for longitudinal magnetic recording which has a coercivity significantly greater than prior CoCrPt thin film media was investigated. A CrMn alloy underlayer was used, instead of the conventional Cr underlayer. A coercivity value of 4280 Oe was easily reached in a CoCrPt film on a 50 nm thick CrMn underlayer as compared to 2810 Oe with a pure Cr underlayer. It was found that the coercivity increase due to the Mn addition was realized if the substrates were preheated before the sputtering. Grain boundary interdiffusion of Mn from the underlayer to the magnetic layer may be the cause for the coercivity increase.