Electric-field-induced spin-flop in BiFeO3 single crystals at room-temperature

TL;DR

This study demonstrates that electric-field-induced polarization re-orientation in BiFeO3 single crystals causes a spin flop, revealing strong coupling between ferroelectric and antiferromagnetic orders at room temperature.

Contribution

It provides direct experimental evidence of electric-field-induced spin-flop in bulk BiFeO3 single crystals, highlighting a potentially stronger coupling than in thin films.

Findings

Electric-field-induced polarization re-orientation causes a spin flop.

Strong coupling between ferroelectric and magnetic orders in bulk.

Confirmation of room-temperature multiferroic behavior in BiFeO3.

Abstract

Bismuth ferrite, BiFeO3, is the only known room-temperature 'multiferroic' material. We demonstrate here, using neutron scattering measurements in high quality single crystals, that the antiferromagnetic and ferroelectric orders are intimately coupled. Initially in a single ferroelectric state, our crystals have a canted antiferromagnetic structure describing a unique cycloid. Under electrical poling, polarisation re-orientation induces a spin flop. We argue here that the coupling between the two orders may be stronger in the bulk than that observed in thin films where the cycloid is absent.