Advanced modeling techniques for micromagnetic systems

Abstract

We present a review of micromagnetic and magnetotransport modeling methods which go beyond the standard model. We first give a brief overview of the standard micromagnetic model, which for (i) the steady-state (equilibrium) solution is based on the minimization of the free energy functional, and for (ii) the dynamical solution, relies on the numerical solution of the Landau-Lifshitz-Gilbert (LLG) equation. We present three complements to the standard model, i.e., (i) magnetotransport calculations based on ohmic conduction in the presence of the anisotropic magnetoresistance (AMR) effect, (ii) magnetotransport calculations based on spin-dependent tunneling in the presence of single charge tunneling (Coulomb blockade) effect, and (iii) stochastic micromagnetics, which incorporates the effects of thermal fluctuations via a white-noise thermal field in the LLG equation. All three complements are of practical importance: (i) magnetotransport model either in the ohmic or tunneling transport regimes, enables the conversion of the micromagnetic results to the measurable quantity of magnetoresistance ratio, while (ii) stochastic modeling is essential as the dimensions of the micromagnetic system reduces to the deep submicron regime and approaches the superparamagnetic limit. Copyright © 2007 American Scientific Publishers All rights reserved.