Infrared and magneto-optical studies of topological insulators Bi$_2$Te$_3$, Sb$_2$Te$_3$ and Bi$_2$Se$_3$

Topological insulators are a main focus in condensed matter physics due to their classification as a new state of matter. They have a unique property in which the bulk of the material is insulating, while the surface states have metallic behavior. We have studied 3D topological insulators Bi2Se3, Bi2Te3 and Sb2Te3 using infrared spectroscopy at vary temperatures to understand their optical properties. Furthermore, we have investigated these materials at vary magnetic fields up to 18 Tesla. Our results reveal strong temperature and magnetic field dependence of optical functions, which indicates unconventional charge dynamics.