Anisotropy of optical absorption of α-MnS single crystal

Abstract

The optical absorption spectra of an α-MnS single crystal and their temperature behavior in the range from 86 to 300 K are investigated for the (100) plane in the energy range from 8×103 to 22×103 cm−1 for the first time. Comparison of these spectra with those for the (111) plane reveals an essential absorption anisotropy in unpolarized light. The anisotropy is manifested in a much stronger splitting of the lowest energy band for the (100) plane in comparison with that for the (111) plane. With decreasing temperature, the splitting becomes smaller. Possible mechanisms for the anisotropy revealed are proposed.