Phenomenological theory of the giant magnetoimpedance of composite wires

TL;DR

This paper presents a phenomenological theory explaining the giant magnetoimpedance effect in three-layer composite wires, successfully matching experimental results and predicting the maximum impedance ratio for specific material combinations.

Contribution

It introduces a coupling of Maxwell and Landau-Lifschitz-Gilbert equations to model the effect without considering domain structures, providing insights into the origin and limits of magnetoimpedance.

Findings

The theory reproduces experimental measurements.

An upper limit of the magnetoimpedance ratio is established.

The model predicts the effect based on material properties.

Abstract

Composite wires with a three-layered structure are known to show a particularly large magnetoimpedance effect. The wires consist of a highly conductive core, an insulating layer and an outer ferromagnetic shell. In order to understand the origin of the effect a theory based on a coupling of the Maxwell equations to the Landau-Lifschitz-Gilbert equation is suggested. The theory is phenomenological in the sense that it does not account for a domain structure. However, theoretical results nicely reproduce those obtained in various measurements. Furthermore, an upper limit of the magnetoimpedance ratio for a given combination of materials can be determined.