Anisotropy and domain structure of die-drawn Co–Si–B amorphous wire with negative magnetostriction (abstract)

Abstract

Domain observation was performed on die-drawn Co–Si–B amorphous wires with negative magnetostriction. We reported previously that die-drawn Fe–Si–B wire with positive magnetostriction shows the characteristic shell and core domain similar to that of as-quenched negatively magnetostrictive Co based wire.1 So it is expected that the domain observation of die-drawn Co based wire will help us understand the process of formation of the core and shell domain structure in die-drawn wires. It was found that the easy axis of magnetization of as-drawn Co based wire is normal to the wire surface and exhibits a maze domain configuration near the wire surface. Its maze domain width is finer than that observed on the as-quenched Fe based wire. The hysteresis loop shows a remanence ratio of around 0.5, from which it is inferred that the die-drawn Co wire has a core domain with longitudinal magnetization underneath the maze domain similar to Fe based wire. It was also found that the relaxation of the anisotropy due to annealing makes the magnetization of the shell domain point in the circumferential direction. This may be related to the two easy axes of anisotropy in the shell domain that are created by the longitudinal tension through negative magnetostriction. Thus, it is inferred that die drawing reverses the direction of the residual stress of the as-quenched wires,2 resulting in the characteristic shell and core domain structure.