Optical conductivity of high-entropy alloys based on BaMnSb₂

The observation of strong bulk nonlinear Hall effect (NLHE) at room temperature in the spin-valley locked Dirac compound BaMnSb₂ has open possibilities for energy applications, such as energy harvesting or terahertz detectors. The band gap and other electronic properties can be tuned through various substitutions at the Ba-site. Here, we present optical reflectance of BaMnSb₂, alloyed at the Ba-site with Ca, Eu and Yb, at various individual concentrations. The reflectance measurements were performed between 300 K and 80 K, in the frequency ranged from 100 cm^-1 to 50 000 cm^-1. From Kramers-Kronig transformation, we obtained various optical functions and discuss the effects of substitution and disorder on the regions of linear frequency dependence of optical conductivity, as a consequence of Dirac band dispersion.