A model for exchange-biased asymmetric giant magneto-impedance in amorphous wires

TL;DR

This paper presents a theoretical model explaining the exchange-biased asymmetric giant magneto-impedance in Joule-heated amorphous wires, linking surface crystalline layers and magnetic coupling to observed impedance behaviors.

Contribution

It introduces a novel model that connects surface crystalline layers and exchange coupling to the asymmetric magneto-impedance in amorphous wires.

Findings

Model qualitatively agrees with experimental impedance data

Impedance depends on magnetic field and frequency

Surface crystalline layer influences magneto-impedance behavior

Abstract

A model describing the exchange-biased asymmetric giant magneto-impedance in Joule-heated amorphous wires is proposed. It is assumed that the Joule heating results in the formation of a surface hard magnetic crystalline layer, and the asymmetric giant magneto-impedance is related to the exchange coupling between the amorphous and crystalline phases. The coupling between the surface layer and the amorphous bulk is described in terms of an effective bias field. The model is based on a simultaneous solution of linearizied Maxwell equations and the Landau-Lifshitz equation. The calculated field and frequency dependences of the wire impedance are in a qualitative agreement with results of the experimental study of the asymmetric giant magneto-impedance in Joule-heated Co-based amorphous wires.