Optical properties of the iron-pnictide analog BaMn 2as 2

Abstract

We have investigated the infrared and Raman optical properties of BaMn 2As 2 in the ab plane and along the c axis. The most prominent features in the infrared spectra are the E u and A 2u phonon modes, which show clear transverse optical-longitudinal optical 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 AFe 2As 2, this compound is much more two dimensional in its electronic properties. For Ec axis, the overall infrared reflectivity is insulatinglike. Within the ab plane, the material exhibits a semiconducting behavior. An energy gap 2Δ=48meV can be clearly identified below room temperature. © 2012 American Physical Society.