Anisotropic Raman Scattering and Lattice Orientation Identification of 2M-WS.

Anisotropic materials with low symmetries hold significant promise for next-generation electronic and quantum devices. 2M-WS, which is a candidate for topological superconductivity, has garnered considerable interest. However, a comprehensive understanding of how its anisotropic features contribute to unconventional superconductivity, along with a simple, reliable method to identify its crystal orientation, remains elusive. Here, we combine theoretical and experimental approaches to investigate angle- and polarization-dependent anisotropic Raman modes of 2M-WS. Through first-principles calculations, we predict and analyze the phonon dispersion and lattice vibrations of all Raman modes in 2M-WS. We establish a direct correlation between their anisotropic Raman spectra and high-resolution transmission electron microscopy images. Finally, we demonstrate that anisotropic Raman spectroscopy can accurately determine the crystal orientation and twist angle between two stacked 2M-WS layers. Our findings provide insights into the electron-phonon coupling and anisotropic properties of 2M-WS, paving the way for the use of anisotropic materials in advanced electronic and quantum devices.