Large-Scale Micromagnetics Simulation of Magnetization Dynamics in a Permanent Magnet during the Initial Magnetization Process

Abstract

For better motors in electric vehicles, we had better understand magnetism at the microscale. Domain-wall motions and magnetization-reversal processes during the initial magnetization process in a hot-deformed Nd${}_{2}$Fe${}_{14}$B permanent magnet are simulated by solving the Landau-Lifshitz-Gilbert equation for a model ensemble of 5302 grains. The initial-magnetization curve reproduces the two-step structure seen in experiment. In the first step, the domain walls move inside the multidomain grains, and the magnetization reversal of the single domains occurs in the second step. The effects of networks among the grains through dipolar interaction are also estimated.