Optical and magneto-optical study of topological insulators Bi$_2$Te$_3$ and Sb$_2$Te$_3$

We have studied electro-dynamical properties of topological insulators Bi$_2$Te$_3$ and Sb$_2$Te$_3$ with the goal of elucidating their electronic structure. Optical and magneto-optical properties of bulk samples of Bi$_2$Te$_3$ and Sb$_2$Te$_3$ will be reported over a broad range of frequencies (from far-infrared to near ultraviolet), temperatures (from room temperature to 4.2 K) and magnetic fields (from zero to 18 Tesla). The spectra reveal strong magneto-optical activity in both Bi$_2$Te$_3$ and Sb$_2$Te$_3$, especially around the plasma minimum in reflectance. From the data we extract some important parameters of charge dynamics, such as carrier mobility and effective mass. The results will be compared and contrasted with similar results on Bi$_2$Se$_3$.