We investigate the charge-density wave (CDW) instability in single and double layers, as well as in the bulk 2H-NbSe2. We demonstrate that the density functional theory correctly describes the metallic CDW state in the bulk 2H-NbSe2. We predict that both monolayer and bilayer NbSe2 undergo a CDW instability. However, while in the bulk the instability occurs at a momentum q(CDW)approximate to 2/3 Gamma M, in freestanding layers it occurs at q(CDW)approximate to 1/2 Gamma M. Furthermore, while in the bulk the CDW leads to a metallic state, in a monolayer the ground state becomes semimetallic, in agreement with recent experimental data. We elucidate the key role that an enhancement of the electron-phonon matrix element at q approximate to q(CDW) plays in forming the CDW ground state.

Effect of dimensionality on the charge-density wave in few-layer 2H-NbSe2 / Calandra, Matteo; Mazin, I. I.; Mauri, Francesco. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 80:24(2009). [10.1103/PhysRevB.80.241108]

Effect of dimensionality on the charge-density wave in few-layer 2H-NbSe2

Mauri, Francesco
2009

Abstract

We investigate the charge-density wave (CDW) instability in single and double layers, as well as in the bulk 2H-NbSe2. We demonstrate that the density functional theory correctly describes the metallic CDW state in the bulk 2H-NbSe2. We predict that both monolayer and bilayer NbSe2 undergo a CDW instability. However, while in the bulk the instability occurs at a momentum q(CDW)approximate to 2/3 Gamma M, in freestanding layers it occurs at q(CDW)approximate to 1/2 Gamma M. Furthermore, while in the bulk the CDW leads to a metallic state, in a monolayer the ground state becomes semimetallic, in agreement with recent experimental data. We elucidate the key role that an enhancement of the electron-phonon matrix element at q approximate to q(CDW) plays in forming the CDW ground state.
2009
charge density waves; density functional theory; electron-phononinteractions; Fermi surface; niobium compounds; semiconductor materials;semiconductor thin films
01 Pubblicazione su rivista::01a Articolo in rivista
Effect of dimensionality on the charge-density wave in few-layer 2H-NbSe2 / Calandra, Matteo; Mazin, I. I.; Mauri, Francesco. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 80:24(2009). [10.1103/PhysRevB.80.241108]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1336823
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