In-plane anisotropic charge dynamics in the layered polar Dirac semimetal BaMnSb2

Abstract

The layered antiferromagnet BaMnSb${}_{2}$ is a polar Dirac semimetal with asymmetrically distorted Sb square lattice. By means of optical spectroscopy and $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ calculations, the authors show here that the lattice asymmetry causes large in-plane anisotropy in the quasi-two-dimensional Dirac band. It is likely that the intersite orbital hybridization in the direction perpendicular to the zigzag chain in the distorted Sb square lattice is selectively reduced due to the crystal symmetry, resulting in a highly anisotropic band dispersion.