The current annealing in Co-based glass-covered amorphous microwires

摘要

The effect of current annealing on magnetic properties and giant magneto-impedance effect of Co-rich glass-covered microwires have been studied. The magnetic properties of four samples that are as cast, Joule-heated under dc current or ac current of 100 Hz or 500 Hz is compared. It was concluded that longitudinal anisotropy dominates the microwire behaviour. But, the inner core with longitudinal anisotropy is surrounded by two concentric outer shells with almost circumferential anisotropies by current annealing. Furthermore, the GMI ratio of the sample under dc current annealing is higher than the GMI ratio of the samples under ac current annealing for the stable magnetic field that induces stronger circumferential anisotropy is produced by dc current annealing.