EFFECT OF MAGNETIC INHOMOGENEITY ON MAGNETIZATION REVERSAL IN SINTERED ND-FE-B MAGNET - NUMERICAL APPROACH

The effect of magnetic inhomogeneity on the magnetization reversal process in a sintered Nd-Fe-B magnet was calculated numerically according to the model where the magnetic anisotropy and the exchange interaction decrease on envelopes of Nd2Fe14B grains. The coercivity in the simulated magnet is determined by the nucleation of a domain wall. Although a local decrease in the anisotropy reduces the nucleation field considerably, a decrease in the exchange interaction has no significant effects on it. The simulated coercive force and its angular dependence can be roughly fitted to the experimental results by assuming that the anisotropy constant is reduced in the 30∼50 Å surface region of Nd2Fe14B grains. © 1990 The Japan Society of Applied Physics.