Optical-absorption spectra of crystal-field transitions in MnPS3 at low temperatures

The manganese thiophosphate (MnPS3) optical-absorption spectrum has been investigated as a function of temperature from 300 down to 10 K in the visible region. With decreasing temperature, the fundamental absorption edge shifts towards higher energies without changing its shape and an additional subband-gap feature appears. This structure has been attributed to transitions between the Mn2+ third excited state and the ground state. All the subband-gap structures exhibit a small temperature shift, in good agreement both with the crystal-field theory and with the so-called transition-metal weakly interacting model. The temperature dependence of the crystal-field parameters Dq, B, and C has been determined from the transition energies. These results support the hypothesis that MnPS3 is to be considered an ioniclike compound, as already suggested in the literature.