Far-infrared cyclotron resonance and Faraday effect in Bi2Se3

The complex Faraday angle and transmission for the topological insulator Bi2Se3 were measured in the far infrared in magnetic fields up to 8 T and analyzed in terms of a simple Drude-Lorentz magnetoplasma dielectric model. Bulk carriers dominate the optical response. The bulk carriers are electrons as we determined from the sign of the Faraday angle. We obtain the bulk band-edge cyclotron mass m(cb) = 0.16 +/- 0.01m(e) and free-electron concentration in the 10(17) range. Electron-phonon interaction effects were found to be weak.