Electromagnon in Y-type hexaferrite BaSrCoZnFe$_{11}$AlO$_{22}$

TL;DR

This study reports the discovery of a room-temperature electromagnon in a Y-type hexaferrite, BaSrCoZnFe$_{11}$AlO$_{22}$, characterized by THz and Raman spectroscopies, and elucidates its activation mechanism via magnetostriction.

Contribution

First observation of a room-temperature electromagnon in BaSrCoZnFe$_{11}$AlO$_{22}$ and analysis of its activation mechanism through combined experimental and theoretical approaches.

Findings

Electromagnon observed at ~1.2 THz with electric polarization along the hexagonal axis.

Electromagnon properties linked to magnetic structure and activated by magnetostriction.

Analytical calculations confirm spin vibrations along the axis activate the electromagnon.

Abstract

We investigated static and dynamic magnetoelectric properties of single crystalline BaSrCoZnFe$_{11}$AlO$_{22}$ which is a room-temperature multiferroic with Y-type hexaferrite crystal structure. Below $300\,\rm K$, a purely electric-dipole-active electromagnon at $\approx 1.2\,\rm THz$ with the electric polarization oscillating along the hexagonal axis was observed by THz and Raman spectroscopies. We investigated the behavior of the electromagnon with applied DC magnetic field and linked its properties to static measurements of the magnetic structure. Our analytical calculations determined selection rules for electromagnons activated by the magnetostriction mechanism in various magnetic structures of Y-type hexaferrite. Comparison with our experiment supports that the electromagnon is indeed activated by the magnetostriction mechanism involving spin vibrations along the hexagonal axis.