Giant domain wall response of highly twinned ferroelastic materials

TL;DR

This paper introduces a Landau-Ginzburg based model to explain the giant elastic softening caused by domain wall motion in ferroelastic materials, with predictions matching experimental data across various compounds.

Contribution

The study develops a theoretical framework that distinguishes domain wall contributions in improper and proper ferroelastic materials, validated by experimental comparisons.

Findings

Excellent agreement between theory and experiments on multiple materials.

Domain wall effects differ significantly between improper and proper ferroelastic materials.

The model accurately predicts superelastic softening phenomena.

Abstract

Many ferroelastic crystals display at sufficiently low measurement frequencies a huge elastic softening below Tc which is caused by domain wall motion. Materials range from perovskites to iron based superconductors and shape memory materials. We present a model - based on Landau-Ginzburg theory including long range elastic interaction between needle shaped ferroelastic domains - to describe the observed superelastic softening. The theory predicts that the domain wall contribution to the elastic susceptibility is different for improper and proper ferroelastic materials. A test of the theory against experimental data on SrTiO3, KMnF3, LaAlO3, La1-xNdxP5O14 and NH4HC2O4.1/2H2O yields excellent agreement.