Polar phonons and spin excitations coupling in multiferroic BiFeO3 crystals

TL;DR

This study reveals the strong coupling between phonons and spin excitations in BiFeO3 crystals, demonstrating how magnetic order influences lattice vibrations and suggesting magnetostriction's significant role in this multiferroic material.

Contribution

It provides experimental evidence of phonon-spin coupling and spin re-orientation effects in BiFeO3 through Raman scattering measurements.

Findings

E and A1 phonon modes are coupled to spin order up to Neel temperature

Low temperature anomalies linked to spin re-orientation observed in phonons and magnons

Magnetostriction is significant in BiFeO3

Abstract

Raman scattering measurements on BiFeO3 single crystals show an important coupling between the magnetic order and lattice vibrations. The temperature evolution of phonons shows that the lowest energy E and A1 phonon modes are coupled to the spin order up to the Neel temperature. Furthermore, low temperature anomalies associated with the spin re-orientation are observed simultaneously in both the E phonon and the magnon. These results suggest that magnetostriction plays an important role in BiFeO3.