Oscillatory non-resonant interband Faraday rotation in InSb and PbTe—a new magneto-optical effect

Abstract

Oscillations in the magnetic field dependence of interband Faraday rotation in degenerate samples of InSb and PbTe at low temperatures have been observed for photons having a wide range of energies which are less than that corresponding to the forbidden energy gap. These oscillations are attributed to the imbalance of contributions from right and left circularly polarized modes to the total rotation, caused by the blocking of certain interband absorptions by conduction-band electrons. The perturbing effect of the variation of carrier concentration is used as an experimental variable. The relative strengths of the oscillations have been reasonably well accounted for by analysis of the interband selection rules and transition strengths given by a theory due to Boswarva & Lidiard. The positions of the oscillations, which depend on the population of Landau levels in the conduction band, have a reciprocal magnetic field dependence as for the de Haas-van Alphen effect, and have yielded quantitative determinations of energy-band parameters.