Anharmonicity and Doping Melt the Charge Density Wave in Single-Layer TiSe2
| Autor: | Matteo Calandra, Francesco Mauri, Lorenzo Monacelli, Raffaello Bianco, Ion Errea, Jianqiang Sky Zhou |
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| Přispěvatelé: | European Commission, Agence Nationale de la Recherche (France), Ministero dell'Istruzione, dell'Università e della Ricerca, Ministerio de Economía y Competitividad (España), Zhou, Jianqiang Sky, Calandra, Matteo, Zhou, Jianqiang Sky [0000-0003-2461-2995], Calandra, Matteo [0000-0003-1505-2535] |
| Rok vydání: | 2020 |
| Předmět: |
Work (thermodynamics)
Charge density waves Materials science fisica Condensed matter physics Band gap Mechanical Engineering Exciton Anharmonicity Exchange interaction Doping Bioengineering 02 engineering and technology General Chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 3. Good health Dichalcogenides Density functional theory General Materials Science 0210 nano-technology Charge density wave |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| ISSN: | 1530-6992 1530-6984 |
| Popis: | arXiv:1910.12709v1 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 TCDW ≈ 440 K for an isolated and undoped single layer and TCDW ≈ 364 K for an electron-doping n = 4.6 × 1013 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 singlelayer TiSe2. Computational resources were granted by PRACE (Project No. 2017174186) and from IDRIS, CINES, and TGCC (Grant eDARI 91202 and Grand Challenge Jean Zay). We acknowledge support from the Graphene Flaghisp core 2 (Grant No. 785219) and Agence nationale de la recherche (Grant No. ANR-19-CE24-0028). F.M. and L.M. acknowledge support by the MIUR PRIN-2017 program, Project No. 2017Z8TS5B. I.E. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (FIS2016- 76617-P). |
| Databáze: | OpenAIRE |
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