Spin-phonon interactions are central to many interesting phenomena, ranging from superconductivity to magnetoelectric effects. Yet, they are believed to have a negligible influence on the structural behavior of most materials. For example, magnetic perovskite oxides often undergo structural transitions accompanied by magnetic signatures whose minuteness suggests that the underlying spin-phonon couplings are largely irrelevant. Here we present an exception to this rule, showing that novel effects can occur as a consequence. Our first-principles calculations reveal that spin-phonon interactions are essential to reproduce the experimental observations on the phase diagram of magnetoelectric multiferroic BiCoO3. Moreover, we predict that, under compression, these couplings lead to an unprecedented temperature-driven double-reentrant sequence of ferroelectric transitions. We propose how to modify BiCoO3 via chemical doping to reproduce such striking effects at ambient conditions, thereby yielding useful multifunctionality.
@article{arxiv.1612.04356,
title = {Multiple structural transitions driven by spin-phonon couplings in a perovskite oxide},
author = {Claudio Cazorla and Oswaldo Dieguez and Jorge Iniguez},
journal= {arXiv preprint arXiv:1612.04356},
year = {2016}
}