Thermal remagnetization of Co5Sm magnets

Abstract

CosSm magnets that are partly or fully demagnetized at room temperature regain some of their magnetization on heating. This phenomenon of thermal remagnetization, which is of importance in several applications, has been characterized as a function of prior treat- ment, magnet shape, temperature, and thermal cycling. A demagneti- zation-remagnetization pretreatment is found to provide stabilization against the effect. Domain studies by the Kerr effect demonstrate that thermal remagnetization in CoSSm results from reduction of micro- scopic magnetostatic energy by domain rearrangement. Because of dif- ferent domain behavior, precipitation-hardened cobalt-rare earth mag- nets exhibit little or no thermal remagnetization.