Magneto-reflectance of Bi$_2$Se$_3$ in 18 Tesla fields

Magneto-optical measurements can provide valuable information in studies of topological insulators. We will report magneto-reflectance spectra of Bi$_2$Se$_3$ in magnetic fields up to 18 Tesla. Magnetic-field induced changes in reflectance are most pronounced around the plasma minimum and around the 60 cm$^{-1}$ mode. Such large magneto-optical activity is unusual for a phonon, and might indicate coupling to collective modes of magnetic origin. Model fits will provide deeper insight into evolution of optical functions with magnetic field.