Temperature dependence of Raman-active modes of TIGaS2 layered crystals: An anharmonicity study

The temperature dependence (16 - 300 K) of unpolarized Raman spectra from TIGaS2 layered crystals was measured in the frequency range of 10 - 400 cm-1. The analysis of the experimental data showed that the temperature dependencies of the phonon frequencies and linewidths were well described by considering the contributions from thermal expansion and lattice anharmonicity. The anharmonic contribution (phonon-phonon coupling) was found to be due to three-phonon processes. The present work demonstrates that the interlayer Raman mode at 42.6 cm-1 shifts toward high frequency as the temperature is raised from 16 to 300 K.