Tailoring of magnetic properties and GMI effect of Co-rich amorphous microwires by heat treatment

Abstract

We studied effect of annealing on Giant magnetoimpedance (GMI) effect and magnetic properties of amorphous Fe and Co-rich microwires. High GMI effect has been observed in as-prepared Co-rich microwires. We observed that changing the annealing conditions we can obtain a great variety of properties in Co-rich microwire. High domain wall (DW) velocity and rectangular hysteresis loops we observed in heat treated Co-rich microwires. We observed increasing of the DW velocity under stress and coexistence of the GMI effect and fast DW propagation in the Co-rich microwires annealed at certain conditions. Fe-rich microwires with similar bulk hysteresis loop do not present considerable GMI effect. We assume that the outer domain shall of the annealed Co-rich microwire exhibiting both fast DW propagation and GMI effect has high circumferential magnetic permeability. Observed fast DW propagation in both kind of microwires is related to the fast magnetization switching within the single domain axially magnetized inner core, i.e. related to the remagnetization process of the inner part of the microwire.