Thermal stability and the magnetization process in CoCrPt-SiO2 perpendicular recording media

The correspondence between the crystallographic texture and intergranular exchange coupling interactions, with the switching mechanism and the thermal response of the magnetization in CoCrPt-SiO2 perpendicular recording media was investigated. Virgin hysteresis and isothermal remanence magnetization measurements both showed a three-stage process, which was interpreted to indicate that the Stoner-Wohlfarth coherent reversal mode is the dominant switching mechanism irrespective of the texture. For media samples with similar degree of texture, improvement in exchange decoupling of the media grains caused an increase in the onset field for the virgin magnetization process. The thermal decay of the magnetization, evaluated via the field-dependent viscosity coefficient peaked near the nucleation field, and the peak value showed a strong dependence on the strength of the exchange coupling interactions. A model establishing the role of the texture and exchange interactions in perpendicular recording media is put forth.