Optical properties of the iron-pnictide analog BaMn2As2

TL;DR

This study explores the infrared and Raman optical properties of BaMn2As2, revealing phonon modes, electronic anisotropy, and a semiconducting gap, contributing to understanding its optical behavior and electronic structure.

Contribution

It provides the first detailed optical characterization of BaMn2As2, highlighting its phonon modes, electronic anisotropy, and energy gap, with results consistent with theoretical calculations.

Findings

Infrared spectra show Eu and A2u phonon modes with TO-LO splitting.

The compound exhibits a semiconducting energy gap of 48 meV.

Electronic properties are more two-dimensional compared to AFe2As2.

Abstract

We have investigated the infrared and Raman optical properties of BaMn2As2 in the ab-plane and along the c-axis. The most prominent features in the infrared spectra are the Eu and A2u phonon modes which show clear TO-LO splitting from the energy loss function analysis. All the phonon features we observed in infrared and Raman spectra are consistent with the calculated values. Compared to the iron-pnictide analog AFe2As2, this compound is much more two-dimensional in its electronic properties. For E || c-axis, the overall infrared reflectivity is insulating like. Within the ab-plane the material exhibits a semiconducting behavior. An energy gap 2{\Delta}=48 meV can be clearly identified below room temperature.