Magneto-mechanical Coupling in Thermal Amorphous Solids

TL;DR

This paper develops a theoretical framework for understanding magneto-mechanical interactions in thermal amorphous solids, addressing the lack of lattice anisotropy and easy axes present in crystalline materials.

Contribution

It introduces a new theory for the mixed responses of amorphous solids to mechanical and magnetic stimuli, including atomistic models tested on bulk and nano-film samples.

Findings

Predictions of magnetostriction in amorphous materials validated.

Nano-film magnetostriction effects with self-affine interfaces analyzed.

Theoretical framework accommodates amorphous structure without easy axes.

Abstract

Standard approaches to magneto-mechanical interactions in thermal magnetic crystalline solids involve Landau functionals in which the lattice anisotropy and the resulting magnetization easy axes are taken explicitly into account. In glassy systems one needs to develop a theory in which the amorphous structure precludes the existence of an easy axis, and in which the constituent particles are free to respond to their local amorphous surroundings and the resulting forces. We present a theory of all the mixed responses of an amorphous solids to mechanical strains and magnetic fields. Atomistic models are proposed in which we test the predictions of magnetostriction for both bulk and nano-film amorphous samples. The application to nano-films with emergent self-affine free interfaces requires a careful definition of the film 'width' and its change due to the magnetostriction effect.