Micromagnetic simulations of thermally activated magnetization reversal of nanoscale magnets

摘要: Numerical integration of a stochastic Landau–Lifshitz–Gilbert equation is used to study dynamic processes in single-domain nanoscale magnets at nonzero temperatures. Special attention given including thermal fluctuations as Langevin term, and the fast multipole method calculate dipole–dipole interactions. It feasible simulate these dynamics on nanosecond time scale for spatial discretizations that involve order 104 nodes using desktop workstation. The considered here are single pillars with large aspect ratio. Hysteresis-loop simulations employed stable metastable configurations magnetization. Each pillar has magnetic end caps. In time-dependent field magnetization observed reverse via nucleation, propagation, coalescence particular, caps propagate into magnet meet near middle. A relatively long-lived defect formed when opposite vort...