Giant directional dichroism of terahertz light in resonance with magnetic excitations of the multiferroic oxide BaCo$_2$Ge$_2$O$_7$

TL;DR

This study demonstrates giant directional dichroism in terahertz light within a multiferroic oxide, BaCo$_2$Ge$_2$O$_7$, by exploiting electromagnon resonances, revealing potential for advanced light control in multiferroics.

Contribution

It shows how multiferroic compounds with electromagnons can produce large directional dichroism at terahertz frequencies, enabling new light-switching functionalities.

Findings

Achieved directional dichroism at terahertz frequencies in BaCo$_2$Ge$_2$O$_7$

Controlled ferroelectric polarization and magnetization influence light absorption

Potential for broad application in multiferroic-based optical devices

Abstract

We propose that concurrently magnetic and ferroelectric, i.e. multiferroic, compounds endowed with electrically-active magnetic excitations (electromagnons) provide a key to produce large directional dichroism for long wavelengths of light. By exploiting the control of ferroelectric polarization and magnetization in a multiferroic oxide Ba$_2$CoGe$_2$O$_7$, we demonstrate the realization of such a directional light-switch function at terahertz frequecies in resonance with the electromagnon absorption. Our results imply that this hidden potential is present in a broad variety of multiferroics.