Coexistence of elastic modulations in the charge density wave state of 2H-NbSe₂
Guster, Bogdan (Institut Català de Nanociència i Nanotecnologia)
Rubio Verdú, Carmen (CIC NanoGUNE700)
Robles, Roberto (Institut Català de Nanociència i Nanotecnologia)
Zaldívar, Javier (CIC NanoGUNE)
Dreher, Paul (Donostia International Physics Center)
Pruneda, Miguel (Institut Català de Nanociència i Nanotecnologia)
Silva-Guillén, Jose Angel (Wuhan University. School of Physics and Technology)
Choi, Deung-Jang (Donostia International Physics Center)
Pascual, José I. (CIC NanoGUNE)
Ugeda, Miguel M. (CIC NanoGUNE)
Ordejon, Pablo (Institut Català de Nanociència i Nanotecnologia)
Canadell Casanova, Enric 1950- (Institut de Ciència de Materials de Barcelona)

Fecha:	2019
Resumen:	Bulk and single-layer 2H-NbSe₂ exhibit identical charge density wave order (CDW) with a quasi-commensurate 3 × 3 superlattice periodicity. Here we combine scanning tunnelling microscopy (STM) imaging at T = 1 K of 2H-NbSe₂ with first-principles density functional theory (DFT) calculations to investigate the structural atomic rearrangement of this CDW phase. Our calculations for single-layers reveal that six different atomic structures are compatible with the 3 × 3 CDW distortion, although all of them lie on a very narrow energy range of at most 3 meV per formula unit, suggesting the coexistence of such structures. Our atomically resolved STM images of bulk 2H-NbSe₂ unambiguously confirm this by identifying two of these structures. Remarkably, these structures differ from the X-ray crystal structure reported for the bulk 3 × 3 CDW which in fact is also one of the six DFT structures located for the single-layer. Our calculations also show that due to the minute energy difference between the different phases, the ground state of the 3 × 3 CDW could be extremely sensitive to doping, external strain or internal pressure within the crystal. The presence of multiphase CDW order in 2H-NbSe₂ may provide further understanding of its low temperature state and the competition between different instabilities.
Ayudas:	European Commission 824143 European Commission 758558 Ministerio de Economía y Competitividad SEV-2017-0706 Ministerio de Economía y Competitividad MAT2017-82074-ERC Ministerio de Economía y Competitividad SEV-2015-0496 Ministerio de Economía y Competitividad FIS2015-64886-C5-3-P Ministerio de Economía y Competitividad FIS2015-64886-C5-4-P Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-1506
Derechos:	Tots els drets reservats.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió acceptada per publicar
Materia:	Charge density waves ; Transition metal dichalcogenides ; DFT calculations ; 2H-NbSe₂ ; STM
Publicado en:	Nano letters, Vol. 19, issue 5 (May 2019) , p. 3027-3032, ISSN 1530-6992

DOI: 10.1021/acs.nanolett.9b00268
PMID: 30998364

Postprint 16 p, 836.4 KB

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Documentos de investigación > Documentos de los grupos de investigación de la UAB > Centros y grupos de investigación (producción científica) > Ciencias > Institut Català de Nanociència i Nanotecnologia (ICN2)
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