Cuscó, R., Taguchi, A., & Yamaguchi, T. (2025). Phonon anharmonicity in α-In2O3: A Raman scattering study of the A1g modes. Journal of Alloys and Compounds, 1020, 179350. https://doi.org/10.1016/j.jallcom.2025.179350

Abstract

We present a temperature dependent Raman scattering study of the A_1g modes of α-In₂O₃. The temperature behavior of the frequency and linewidth of the high and low frequency A_1g Raman peaks is analyzed using a perturbation theory model of anharmonic decay including 3- and 4-phonon processes. Possible decay channels are identified in the light of density functional perturbation theory calculations of the phonon dispersion. A very different anharmonic behavior of the two A_1g modes is observed. The low-frequency mode shows an unusually small linewidth because of the dominance of upconversion channels due to the lack of lower-energy optical modes for anharmonic decay. In contrast, 3-phonon decay into lower energy optical modes dominates the high frequency mode, which shows a linear increase in linewidth with temperature. The anharmonic decay model fitted to the Raman data gives an excellent agreement with the experiment and allows the relative strength of 3- and 4-phonon channels to be assessed.