Magnetic disaccommodation phenomena in rare-earth intermetallic compounds

On the R(2)Fe(14)B (R = rare earth) pure and hydrogenated compounds a systematic ac magnetic susceptibility study has been performed, to determine the origin of a frequently observed anomaly, nonrelated to the spin reorientation transitions. We have been able to induce the anomaly by thermal annealing the ingots, and to increase its height increasing both rile annealing lime and temperature. This susceptibility anomaly has been correlated with a similar one found for the same samples, at the same temperature in magnetic aftereffect (MAE) measurements. We conclude that the anomaly is caused by magnetic disaccommodation of point defects coupled to tile domain walls. Based on this mechanism a pimple model is proposed, which interprets the phenomenology of this type of anomalies. For all samples measured and with activation energy and relaxation time parameters for th domain wall motion (coupled to defects) obtained from MAE experiments, the nai and imaginary components of the susceptibility data have been fitted to the appropriate analytical expressions.