Thermomechanics of ferri-antiferromagnetic phase transition in finitely-strained rocks towards paleomagnetism

TL;DR

This paper develops a comprehensive thermomechanical model for rocks undergoing ferri-antiferromagnetic phase transitions, incorporating viscoelasticity, magnetization dynamics, and thermodynamic consistency to explain paleomagnetic phenomena.

Contribution

It introduces a fully Eulerian, rate-based thermodynamic model that integrates phase transition, magnetization, and viscoelasticity for crustal rocks.

Findings

Model captures thermoremanent paleomagnetism in rocks.

Incorporates mechanically dependent exchange energy.

Ensures energy conservation and entropy inequality.

Abstract

The thermodynamic model of visco-elastic deformable magnetic materials at finite strains is formulated in a fully Eulerian way in rates with the aim to describe thermoremanent paleomagnetism in crustal rocks. The Landau theory applied to a ferro-to-para-magnetic phase transition, the gradient theory for magnetization (leading to exchange energy) with general mechanically dependent coefficient, hysteresis in magnetization evolution by Gilbert equation involving objective corotational time derivative of magnetization, and demagnetizing field are considered in the model. The Jeffreys viscoelastic rheology is used with temperature-dependent creep to model solidification or melting transition. The model complies with energy conservation and the Clausius-Duhem entropy inequality.