Raman scattering and phase transitions ofV2O3

Abstract

Raman scattering in single crystals of ${\mathrm{V}}_2$ ${\mathrm{O}}_3$ has been studied in the range from ∼20 K to room temperature. Metal to insulator, crystallographic, and antiferromagnetic-ordering transitions take place concurrently at $T_t\sim 150$ K. The observed spectra showed a drastic change at $T_t$. On either side of $T_t$, peaks were observed which had intensities rather insensitive to the variation of temperature. These peaks are identifiable as phonon excitations, and the peaks of the two temperature regions can be correlated on the basis of the structural transition of the crystal. One peak was observed in the low-temperature region, the intensity of which decreased strongly with increasing temperature, becoming unobservable at $T\gtrsim T_t$. Clearly, this peak involved the excitation of magnons which resulted from the magnetic transition.