Micromagnetic simulation of thermally assisted magnetization reversal in magnetic nanodots with perpendicular anisotropy

Temporal evolution of magnetization in a field cooling process from magnetic ordering temperature has been numerically investigated for magnetic nanodots with perpendicular anisotropy by solving the stochastic Landau-Lifshitz-Gilbert equation. The magnetic field required to align the magnetization, i.e. the switching field for thermally assisted writing of magnetic dot, depends on not only the intrinsic anisotropy field but also the magnetization reversal mechanism. To minimize the switching field with ensuring a practical thermal stability of the dot for nonvolatile memory applications, the lateral dimension of the dot should be smaller than its critical size for single domain configuration to avoid a formation of flux closure configuration inside the dot.