Giant magnetoimpedance of composite wires with an insulation layer

TL;DR

This study investigates the giant magneto-impedance effect in composite wires with a three-layer structure, combining experimental measurements and theoretical modeling to understand their potential in magnetic sensors.

Contribution

It introduces a new composite wire structure with an insulation layer and develops a coupled theoretical model to explain GMI behavior, supported by experimental validation.

Findings

GMI ratio varies with current frequency and insulation thickness

Theoretical model accurately predicts impedance behavior

Composite wires show promise for sensitive magnetic sensors

Abstract

Composite wires with a three-layered structure exhibit a large giant magneto-impedance (GMI) effect, which can be used in sensitive magnetic field sensors. To further investigate the origin of the GMI effect, composite wires consisting of a highly conductive copper core, a silicon dioxide layer and an outer Permalloy shell were prepared by radio frequency (RF) magnetron sputtering. The GMI ratio was measured at various driving current frequencies and with different insulating layer thicknesses. A theoretical model by coupling the Maxwell equations to the Landau-Lifschitz-Gilbert equation was developed to investigate the composite wire impedance and its dependence on external magnetic field, current frequency and insulating layer thickness. Experimental results corroborate the theoretical model.