Low-dimensional systems with a vanishing band gap and a large electron-hole interaction have been proposed to be unstable toward exciton formation. As the exciton binding energy increases in low dimension, conventional wisdom suggests that excitonic insulators should be more stable in 2D than in 3D. Here we study the effects of the electron-hole interaction and anharmonicity in single-layer TiSe2. We find that, contrary to the bulk case and to the generally accepted picture, in single-layer TiSe2, the electron-hole exchange interaction is much smaller in 2D than in 3D and it has weak effects on phonon spectra. By calculating anharmonic phonon spectra within the stochastic self-consistent harmonic approximation, we obtain T-CDW approximate to 440 K for an isolated and undoped single layer and T-CDW approximate to 364 K for an electron-doping n = 4.6 x 10(13) cm(-2), close to the experimental result of 200-280 K on supported samples. Our work demonstrates that anharmonicity and doping melt the charge density wave in single-layer TiSe2.

Anharmonicity and Doping Melt the Charge Density Wave in Single-Layer TiSe2 / Zhou, Jqs; Monacelli, L; Bianco, R; Errea, I; Mauri, F; Calandra, M. - In: NANO LETTERS. - ISSN 1530-6984. - 20:7(2020), pp. 4809-4815. [10.1021/acs.nanolett.0c00597]

Anharmonicity and Doping Melt the Charge Density Wave in Single-Layer TiSe2

Bianco, R;
2020

Abstract

Low-dimensional systems with a vanishing band gap and a large electron-hole interaction have been proposed to be unstable toward exciton formation. As the exciton binding energy increases in low dimension, conventional wisdom suggests that excitonic insulators should be more stable in 2D than in 3D. Here we study the effects of the electron-hole interaction and anharmonicity in single-layer TiSe2. We find that, contrary to the bulk case and to the generally accepted picture, in single-layer TiSe2, the electron-hole exchange interaction is much smaller in 2D than in 3D and it has weak effects on phonon spectra. By calculating anharmonic phonon spectra within the stochastic self-consistent harmonic approximation, we obtain T-CDW approximate to 440 K for an isolated and undoped single layer and T-CDW approximate to 364 K for an electron-doping n = 4.6 x 10(13) cm(-2), close to the experimental result of 200-280 K on supported samples. Our work demonstrates that anharmonicity and doping melt the charge density wave in single-layer TiSe2.
2020
20
7
4809
4815
Anharmonicity and Doping Melt the Charge Density Wave in Single-Layer TiSe2 / Zhou, Jqs; Monacelli, L; Bianco, R; Errea, I; Mauri, F; Calandra, M. - In: NANO LETTERS. - ISSN 1530-6984. - 20:7(2020), pp. 4809-4815. [10.1021/acs.nanolett.0c00597]
Zhou, Jqs; Monacelli, L; Bianco, R; Errea, I; Mauri, F; Calandra, M
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

Licenza Creative Commons
I metadati presenti in IRIS UNIMORE sono rilasciati con licenza Creative Commons CC0 1.0 Universal, mentre i file delle pubblicazioni sono rilasciati con licenza Attribuzione 4.0 Internazionale (CC BY 4.0), salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/1299819
Citazioni
  • ???jsp.display-item.citation.pmc??? 3
  • Scopus 23
  • ???jsp.display-item.citation.isi??? 21
social impact