Huge Spin-Driven Polarizations at Room-Temperature in bulk BiFeO3

TL;DR

This study reveals two significant hidden spin-driven polarizations in room-temperature BiFeO3, surpassing other multiferroics, by combining first-principles calculations and spin models to uncover underlying symmetry-breaking mechanisms.

Contribution

It uncovers two large hidden spin-driven polarizations in BiFeO3 linked to different symmetry breakings, providing new insights into magnetoelectric couplings in multiferroics.

Findings

First polarization reaches 3.0 μC/cm², larger than in other multiferroics.

Identification of two types of symmetry-breaking related polarizations.

Provides a pathway to discover hidden magnetoelectric effects in similar materials.

Abstract

The spin-driven polarizations of type-I multiferroics are veiled by the preexisting ferroelectric (FE) polarization. Using first-principles calculations combined with a spin model, we uncover two hidden but huge spin-driven polarizations in the room-temperature multiferroic BiFeO3. One is associated with the global inversion symmetry broken by a FE distortion and the other is associated with the local inversion symmetry broken by an antiferrodistortive octahedra rotation. Comparison with recent neutron scatterings reveals that first polarization reaches 3.0 $\mu$C/cm$^2$, which is larger than in any other multiferroic material. Our exhaustive study paves a way to uncover the various magnetoelectric couplings that generate hidden spin-driven polarizations in other type-I multiferroics.