Optical magnetoelectric effect in the polar honeycomb antiferromagnet Fe2Mo3O8

TL;DR

This study investigates the optical magnetoelectric effects in the polar honeycomb antiferromagnet Fe2Mo3O8, demonstrating nonreciprocal directional dichroism and modeling THz excitations with a combined experimental and theoretical approach.

Contribution

It provides a comprehensive experimental and theoretical analysis of THz excitations and nonreciprocal effects in Fe2Mo3O8, advancing understanding of optical magnetoelectric phenomena in polar antiferromagnets.

Findings

Successful modeling of THz excitations using a single-ion approach.

Observation of nonreciprocal directional dichroism in Fe2Mo3O8.

Temperature dependence of electronic transitions in infrared range.

Abstract

The lack of both time-reversal and spatial inversion symmetry in polar magnets is a prerequisite for the occurrence of optical magnetoelectric effects such as nonreciprocal directional dichroism with the potential for the realization of optical diodes. In particular, antiferromagnetic materials with magnetic excitations in the THz range such as Fe2Mo3O8 are promising candidates for next-generation spintronic applications. In a combined experimental and theoretical effort we investigated the THz excitations of the polar honeycomb antiferromagnet Fe2Mo3O8 in external magnetic fields and their nonreciprocal directional dichroism, together with the temperature dependence of the electronic transitions in the mid- and near-infrared frequency range. Using an advanced single-ion approach for the Fe ions, we are able to describe optical excitations from the THz to the near-infrared frequency range quantitatively and successfully model the observed nonreciprocal directional dichroism in the THz regime.