Observation of electromagnon excitations in the BiFe0$_3$ spiral magnet

TL;DR

This study uncovers electromagnon excitations in BiFeO3, revealing their spectral characteristics and providing insights into the coupling between ferroelectric and magnetic orders in multiferroic materials.

Contribution

First experimental observation of electromagnon spectra in BiFeO3 using low energy inelastic light scattering, highlighting two distinct electromagnon modes.

Findings

Identification of two electromagnon species in BiFeO3

Electromagnons couple to optical phonons in the material

Insights into the interplay between ferroelectric and magnetic orders

Abstract

Recently, oxide multiferroics have attracted much attention due to their large magnetoelectric effect which allows the tuning of magnetic properties with electric field and vice versa and open new venues for future spintronic applications such as multiple-state memory devices with dual magnetic and electric control. BiFeO$_3$ (BFO) belongs to this new class of materials and shows both ferroelectric and antiferromagnetic orders at room temperature with a large electric polarizationassociated with a cycloidal spiral magnetic ordering. The incommensurate magnetic order induces magnon zone folding and allows investigations by optical probes of unusual spin waves which couples to optical phonons, the so called "`electromagnons"'. Here, we unravel for the first time the electromagnon spectra of BFO by means low energy inelastic light scattering technique. We show the existence of two species of electromagnons corresponding to spin wave excitations in and out of the cycloidal plane. The present observations present an unique opportunity to study the interplay between ferroelectric and magnetic orders.