Optical Faraday Effect of II–VI Compound Crystals

Abstract

Faraday effect of various IIb–VIb compound crystals, including ZnS, CdS, ZnO, ZnSe, and ZnTe, was measured at frequencies just below the fundamental absorption edge down to lower frequencies. Observed Faraday rotations were interpreted in terms of the intrinsic interband electronic transitions, and attempts were made to fit the observed spectral dependences of the rotation with theoretical expressions for the interband Faraday effect. The preliminary results show that the dispersive behaviors of the rotation observed in the crystals quoted above at room and low temperatures can be described fairly well by the theoretical expression given by Boswarva et al. for the simple direct interband transition. The agreement is especially satisfactory in the case of ZnS, yielding the values of 3.752 and 3.871 eV as the direct band gap energies at 286 and 107°K, respectively. It is supposed that the similarity found in the spectral behaviors of the Faraday rotations of these II–VI compounds indicates that the fundamental absorptions in these crystals are associated with the allowed direct interband transitions.