Domain-Wall Processes in SmCo5 Powders

Abstract

Measurements of minor loops of SmCo₅ powders have revealed that wall motion is predominant in the magnetization process. A relation between the reversible susceptibility χ of the minor loops and the coercivity H_c has been found, showing that the coercivity of the investigated material is determined by the pinning of domain walls, rather than nucleation. The relation χH_c²=const has been found in a wide range of coercivities obtained by aging of the material. The aging process is interpreted as a decrease of the density of pinning sites, each site retaining its pinning force. Hysteresis loops measured on single particles of a few microns size confirm these interpretations and allow for a refined model of pinned‐wall coercivity of SmCo₅ powders.