Polarized Raman Spectroscopy of 2H-NbSe2 and 1T-VSe2 Single Crystals
Journal
Journal of Raman Spectroscopy
ISSN
10974555
03770486
Date Issued
2025
Author(s)
Annawati, Bergitta Dwi
Arun Kumar, Kalingarayanpalayam Matheswaran
Chang, Yuchen
Chen, Shihchieh
Lu, T. H.
Huang, Xianglin
Lan, Yinping
Shu, Guojiun
Saito, Riichiro
Abstract
We present the polarized Raman spectra of 2H-NbSe (Formula presented.) and 1T-VSe (Formula presented.) single crystals. The phonon symmetries of the first-order Raman-active modes in both materials are identified using linearly and circularly polarized Raman spectroscopy. In particular, the Raman peak of 1T-VSe (Formula presented.) at 250 cm (Formula presented.), previously assigned to the E (Formula presented.) mode, is reinterpreted as two-phonon combinational modes at the M point in the Brillouin zone. The helicity-dependent Raman spectroscopy enables the separation of the overlapping A (Formula presented.) and E (Formula presented.) modes in 2H-NbSe (Formula presented.). The second-order phonon modes exhibit either helicity-conserving or helicity-changing behavior. The first-principles calculations of phonon dispersion and the two-phonon density of states support the assignment of the two-phonon modes. The calculated shear and layer breathing modes of 2H-NbSe (Formula presented.) appear at 37 and 53 cm (Formula presented.), respectively, while the calculated E (Formula presented.) mode of 1T-VSe (Formula presented.) appears at 139 cm (Formula presented.).
Publisher
John Wiley and Sons Ltd
Type
review article