Influence of bias voltage on the switching behaviour of CoCrPt–SiO2 perpendicular recording media

Abstract

A systematic investigation of the influence of negative substrate bias on the microstructure and magnetic switching behaviour of CoCrPt : SiO2 perpendicular recording media is performed by varying the negative bias voltage from 0 to 600 V during the deposition of a bottom Ru (or Ru : TiO2SiO2) intermediate layer. The microscopic structures and the surface morphology are studied by a transmission electron microscope and an atomic force microscope. The crystallographic properties are studied by an x-ray diffractometer. Our observation shows that high biasing is at work to favour the formation of low-energy hexagonal close packed (0 0 2) planes, resulting in high crystallinity of Ru. Addition of oxide to the Ru intermediate layer leads to an increase in grain segregation, which results in a small grain diameter, but broad standard deviation and large surface roughness. Utilization of a bias voltage on the Ru oxide intermediate layer successfully improves the crystal texture of CoCrPt : SiO2 and induces high Hc, a narrow intrinsic switching field distribution and low Hcr45/Hcr0, while maintaining isolated grains and small grain size.