Low-Temperature Raman Spectra of YbVO4

This paper reports on the spectroscopic study of YbVO4 in the range 10-300 K. All the Raman phonons were properly assigned. Temperature-dependent Raman spectra showed no anomalous changes, which indicate that neither structural phase transition nor strong electron-phonon coupling occur, at least within this temperature range. This result is sharp contrast to those of YbPO4 where strong mixing of the upper crystal-field states Γ6 and Γ7 with an Eg3 phonon at room-temperature occurs. A possible explanation for the absence of electron-phonon coupling in YbVO4 is the occurrence of the Γ6 state at energy higher than the Eg3 phonon, unlike the coincidence of Γ6 and Eg3 energies in YbPO4.