Raman scattering investigation of large positive magnetoresistance material WTe_2

摘要

We have performed polarized Raman scattering measurements on WTe_2, for which an extremely large positive magnetoresistance has been reported recently. We observe 5 A_1 phonon modes and 2 A_2 phonon modes out of 33 Raman active modes, with frequencies in good accordance with first-principles calculations. The angular dependence of the intensity of the peaks observed is consistent with the Raman tensors of the C_(2υ) point group symmetry attributed to WTe_2. Although the phonon spectra suggest neither strong electron-phonon nor spin-phonon coupling, the intensity of the A_1 phonon mode at 160.6cm~(-1) shows an unconventional decrease with temperature decreasing, for which the origin remains unclear.