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Stable charge density wave phase in a 1T-TiSe2 monolayer

TitleStable charge density wave phase in a 1T-TiSe2 monolayer
Publication TypeJournal Article
Year of Publication2017
AuthorsSingh, Bahadur, Hsu Chuang-Han, Tsai Wei-Feng, Pereira Vitor M., and Lin Hsin
JournalPhys. Rev. B
Date Published06/2017
Keywordsdiselenide, metal, spectrum, tise2, transition

Charge density wave (CDW) phases are symmetry-reduced states of matter in which a periodic modulation of the electronic charge frequently leads to drastic changes of the electronic spectrum, including the emergence of energy gaps. We analyze the CDW state in a 1T-TiSe2 monolayer within a density functional theory framework and show that, similarly to its bulk counterpart, the monolayer is unstable towards a commensurate 2x2 periodic lattice distortion (PLD) and CDWat low temperatures. Analysis of the electron and phonon spectrum establishes the PLD as the stable T = 0 K configuration with a narrow band gap, whereas the undistorted and semimetallic state is stable only above a threshold temperature. The lattice distortions as well as the unfolded and reconstructed band structure in the CDW phase agree well with experimental results. We also address evidence in our results for the role of electron-electron interactions in the CDW instability of 1T-TiSe2 monolayers.


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