2020/05/22 by Sugata Chowdhury, Chowdhury, Sugata, Albert F. Rigosi +13 · 1 citation
Engineering · Materials Science · Physics and Astronomy · #2D Materials and Applications #Chalcogenide Semiconductor Thin Films #Machine Learning in Materials Science #cond-mat.mtrl-sci
paper · pdf · doi:10.48550/arxiv.2005.11350
6 figures, 28 pages
arxiv created 2021/08/21 · arxiv updated 2021/08/24
Metallic transition metal dichalcogenides like tantalum diselenide (TaSe2) exhibit exciting behaviors at low temperatures, including the emergence of charge density wave (CDW) states. In this work, density functional theory (DFT) is used to investigate how structural, electronic, and Raman spectral properties of the CDW configuration change as a function of thickness. Such findings highlight the influence of dimensionality change (from 2D to 3D) and van der Waals (vdW) interactions on the system properties. The vdW effect is most strongly present in bulk TaSe2 in the spectral range 165 cm-1 to 215 cm-1. The phonons seen in the experimental Raman spectra are compared with the results calculated from the DFT models as a function of temperature and layer number. The matching of data and calculations substantiates the model's description of the CDW structural formation as a function of thickness, which is shown in depth for 1L through 6L systems. These results highlight the importance of understanding interlayer interactions, which are pervasive in many quantum phenomena involving two-dimensional confinement.