INTERACTIONS AND MAGNETIC VISCOSITY - NONMONOTONIC TIME-VARIATION OF THE MAGNETIZATION DURING RELAXATION AT CONSTANT DEMAGNETIZING FIELD

We present magnetic relaxation data of PrNdFeB magnets. These data wer e obtained by measuring the time evolution of the magnetization under constant applied demagnetizing fields. The results corresponding to fi elds far from the range of the coercive force evidenced a nonmonotonic time variation of the magnetization. We propose that the occurrence o f magnetic interactions underlies the observed anomalous behavior. Thi s idea is checked through a micromagnetic simulation of the time evolu tion of the magnetization of a low field reversed nucleus which is exc hange and magnetostically coupled to the main hard phase. (C) 1996 Ame rican Institute of Physics.