Recording Properties of Co-Based Alloy Heat-Treated Media

Abstract

The recording properties of Co-based alloy heat-treated media using carbon substrates with high heat resistance were investigated. For media with the same H _c , the amplitude and media noise of the CoCrTa media were lower than those of CoNiCr and CoCrPt media, because of the lower B _r δ (where δ is the thickness of the Co-based alloy layer). For CoNiCr media with the same B _r δ, the media noise decreased with increasing H _c , that is, with increasing heat treatment temperature. Analyses of the rotational hysteresis loss using a highly sensitive torque magnetometer and high resolution scanning transmission electron microscopy (HRSTEM) showed that the values of H _c /H _k ^grain increased to 0.44 with increasing H _c , and that the Cr concentration at the grain boundaries of the CoNiCr also increased. It is therefore thought that the reduction in noise was achieved as a result of reduced exchange coupling between grains.