Arrhenius–Néel thermal decay in polycrystalline thin film media

A simple expression for the remanent coercivity versus field time duration has been developed for polycrystalline thin film media with two-dimensional random anisotropy axis orientation. Explicit averaging of the thermally induced reversal for random grains is shown to be well approximated by the thermal decay of one particle with anisotropy axis at an angle of ≈21° to the applied field. The expression has no adjustable parameters and two slightly different forms apply to noninteracting and weakly interacting grains. Applicability is shown to be for times greater than approximately 100 ns. Good agreement is shown with measurements on two series of thin films with varying coating thickness.