Magnetism in Co80-xFexB20: Effect of crystallization

Abstract

We report on the change in the structural and magnetic properties of magnetically soft ternary Co80-xFexB20 alloys as a function of composition, thickness, and annealing temperature. Compositions high in cobalt show a significant change in coercivity after annealing. This is explained using the random anisotropy model by relating the magnetic exchange length to the grain size of the crystallites. The presented results are a systematic study explaining trends seen in the transition from soft to hard magnetic behavior, providing insight into why the soft CoFeB alloys have been so successful recently in spintronic devices.