Direct coupling of ferromagnetic moment and ferroelectric polarization in BiFeO$_3$

TL;DR

This study demonstrates the direct coupling between ferromagnetic moments and ferroelectric polarization in BiFeO$_3$, showing magnetic field control of electric polarization through experimental measurements and theoretical modeling.

Contribution

It provides experimental evidence of magnetoelectric coupling in BiFeO$_3$ and confirms the metal-ligand hybridization model as a mechanism.

Findings

Electric polarization normal to the c axis observed in multiple magnetic phases.

Ferromagnetic moment directly coupled with electric polarization in the canted antiferromagnetic phase.

Magnetoelectric coupling explained by the metal-ligand hybridization model.

Abstract

The spin-driven component of electric polarization in a single crystal of multiferroic BiFeO$_{3}$ was experimentally investigated in pulsed high magnetic fields up to 41 T. Sequential measurements of electric polarization for various magnetic field directions provide clear evidence of electric polarization normal to the hexagonal $c$ axis (${\bf P}_{\rm t}$) in not only the cycloidal phase, but also the field-induced canted antiferromagnetic phase. The direction of ${\bf P}_{\rm t}$ is directly coupled with the ferromagnetic moment in the canted antiferromagnetic phase, and thus controlled by changing the direction of the applied magnetic field. This magnetoelectric coupling is reasonably reproduced by the metal-ligand hybridization model.