  Magneto-optical permittivity tensor spectra of undoped InSb, n-doped and
p-doped InSb crystals were determined using the terahertz time-domain
spectroscopy (THz-TDS) and the Fourier transform far-infrared spectroscopy
(far-FTIR). A Huge polar magneto-optical (MO) Kerr-effect (up to 20 degrees in
rotation) and a simultaneous plasmonic behavior observed at low magnetic field
(0.4 T) and room temperature are promising for terahertz nonreciprocal
applications. We demonstrate the possibility of adjusting the the spectral rage
with huge MO by increase in n-doping of InSb. Spectral response is modeled
using generalized magneto-optical Drude-Lorentz theory, giving us precise
values of free carrier mobility, density and effective mass consistent with
electric Hall effect measurement.
