Dynamic-thermal effects in thin film media

Thermal dynamic effects are discussed for both short write times and long s torage times in thin film media. A new analytic model for coercivity versus pulse time for the entire time range is presented for planar random media. Neel-Arrhenius analysis is shown to be accurate only for times greater tha n about 100-1000 nsec. The effective volume in the long time Neel-Arrhenius regime is the rms volume for a distribution of grain sizes. For planar ran dom media the volume is increased about 7% and is independent of intergranu lar interactions. The presence of a small K-2 hexagonal anisotropy in typic al Co based alloys increases the stability, but has less effect on the intr insic reversal field and the short time dynamic writing field. Increasing t he damping constant may significantly reduce the write field, but, for both longitudinal and perpendicular media, yields only a very small increase in the thermal decay. Analysis of short time write fields in terms of a "swit ching constant" is shown not to be fundamental to these hard materials.