Arrhenius-Neel 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 in duced reversal for random grains is shown to be well approximated by the th ermal decay of one particle with anisotropy axis at an angle of approximate to 21 degrees to the applied field. The expression has no adjustable param eters and two slightly different forms apply to noninteracting and weakly i nteracting grains. Applicability is shown to be for times greater than appr oximately 100 ns. Good agreement is shown with measurements on two series o f thin films with varying coating thickness. (C) 1999 American Institute of Physics. [S0021-8979(99)62008-4].