Cell size corrections for nonzero-temperature micromagnetics

Micromagnetic calculations at nonzero temperatures depend on the computational cell size. This paper shows that the spontaneous magnetization M-S of exchange-coupled moments has to be scaled by a Bloch-like law, which is similar to the well-known temperature dependence of M-S. Using this scaling law, nonatomistic Metropolis Monte Carlo and stochastic Landau-Lifshitz-Gilbert simulations are performed in an external field of 0.1 T. The error of the equilibrium magnetization at a temperature of T/T-C=0.38 and a cell size of 1.5 nm is then 0.9% as compared with atomistic calculations. In contrast, a cell size-independent M-S leads to an overestimation of the temperature of 3.2%. (c) 2005 American Institute of Physics.