Langevin Micromagnetics of Recording Media using Subgrain Discretization

Thomas Schrefl, Werner Scholz, Dieter Süss and Josef Fidler

IEEE Trans. Mag., 36 (2000) 3189 - 3191



Finite element based micromagnetics is applied to study thermally assisted switching of thin film media in the high speed regime. The space discretization leads to a system of sto-chastic differential equations with multiplicate noise which is interpreted in the sense of Stratonovich and solved using the method of Heun. For a CoCrPt alloy system, an external field of 240 kA/m was found to be sufficient to switch the magnetization in less than 1 ns in about 80% of the realizations of the stochastic process. However, reversal times up to 10 ns and higher are observed for about 15% of the calculations. Then the system switches from the high remanent state to a meta-stable state where it remains trapped for several nanoseconds.


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Feb. 13, 2001