Anisotropic terahertz conductivity in antiferromagnet Weyl semimetal Mn3Sn epitaxial thin films

The interaction of terahertz (THz) wave with condensed matter material is utilized to investigate the low-energy electronic behaviors and topological properties near its equilibrium state, for example, transport characteristics of topological semimetals. Notably, antiferromagnetic Weyl semimetal (WSM) Mn3Sn has attracted vast attention owing to markedly anomalous effects, such as room-temperature anomalous Hall effect. Here, we investigate the thickness-dependent THz conductivity of Mn3Sn epitaxial films by polarization-resolved THz time-domain spectroscopy, which can be attributed to the Berry curvature induced near the Weyl nodes in the momentum space. The THz longitudinal conductivities of high-quality Mn3Sn epitaxial thin films are anisotropic along different crystal orientations with carrier localization behavior, which are well described by the Drude-Smith model. By combining first-principles calculations with a comparison between theoretical and experimental carrier concentrations, this study demonstrated that the THz conductivity of the Mn3Sn thin film is jointly determined by intraband transitions of free carriers. These results have deepened the understanding of THz conductivity in the antiferromagnetic WSM Mn3Sn epitaxial thin films. The interaction of terahertz (THz) waves with condensed matter materials is utilised to investigate the low-energy electronic behaviours and topological properties near the equilibrium state, for example, transport characteristics of topological semimetals. Here, the THz longitudinal conductivities of high-quality Mn3Sn epitaxial thin films are anisotropic along different crystal orientations with carrier localization behavior, which are well described by the Drude-Smith model.