Raman Tensor of Layered Td-WTe2

Weyl semimetal Td-WTe2 has attracted extensive attention due to its abundant physical properties. Further study on Td-WTe2 crystal structure is helpful for its understanding and modification in application. In this article, a method for studying crystal symmetry based on Raman tensor is proposed. Specifically, it analyzed the anisotropy of the material structure by the angle-resolved polarized Raman spectroscopy and discussed the Raman selection rules and the physical image of the Raman tensor matrix element in depth, which filled in the deficiency of information on Raman tensor elements obtained simply by experiments. According to the study and discussion, the basal and cross plane of Td-WTe2 crystal show incompletely consistent polarization dependence of Raman scattering intensity. Combined with theoretical calculations and angle-resolved Raman spectrum experiments, the corresponding Raman tensor elements of each vibration mode are obtained. The dominant vibration orientation of each mode depends on the differential polarizability corresponding to the Raman tensor element. For the comparison of shrinkage degrees, the mode with larger shrinkage degree tends to vibrate along the c-axis. The results provide a new way for studying the Raman tensor of other transition metal chalcogenides and offers a noble direction for the application of anisotropic thin materials.