The effect of the cell size in Langevin micromagnetic simulations

Abstract Langevin micromagnetics treats finite temperature effects by adding a thermal fluctuation field, Hth, to the effective field. If combined with the finite element method or the finite difference method, the spatial correlation length of the random field is usually taken to be equal to the cell size of the computational grid. The influence of the cell size has been studied for two different systems: a system close to equilibrium and a system which exhibits thermal activated switching. The results suggest that the calculated properties are independent of the cell size if the cell size is smaller than the thermal exchange length A/(J s H th ) . The term A is the exchange constant and Js is the spontaneous magnetic polarization. Below this critical length the magnetization is uniform.