Influence of heat and compression treatment on magnetic and demagnetization properties of CoCr perpendicular magnetic recording media

Abstract

AbstractCoCr alloy thin films considered useful for perpendicular magnetic recording media and films deposited by vacuum evaporation and sputtering have been evaluated. In this study, a CoCr was vacuum‐deposited on Ge underlayers to prepare preferentially oriented films in the c‐axis direction. The influences of the thermal and pressure treatments on the magnetic properties were investigated. The influences of thermal and pressure treatments on the remanence magnetization where the magnetization was carried out in one direction normal to the film surface and the perpendicular magnetic recording were also investigated. As a result, it was found that the thermal treatment at a temperature higher than the deposition temperature reduced the saturation magnetization and increased the perpendicular coercivity and perpendicular magnetic aniso‐tropy. The amount of these changes was greater for the films deposited at lower substrate temperature which had smaller coercivity values. The changes in the magnetic properties were thought to be due to the Cr diffusion during heat treatment. On the other hand, during the pressure treatment, no change in the magnetic properties was observed. The decrease of magnetization due to the thermal treatment was smaller when a film was recorded perpendicularly magnetic than when it was magnetized in one direction perpendicular to the film surface. The decrease of the magnetization was smaller as the recording density increased. In the pressure treatment, the remanence magnetization where magnetization occurred in one direction decreased monotonically as the applied pressure increased. On the other hand, when the perpendicular magnetic recording was carried out on films, less decrease in magnetization was observed.