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Coexistence of elastic modulations in the charge density wave state of 2H-NbSe₂
- Source :
- Dipòsit Digital de Documents de la UAB, Universitat Autònoma de Barcelona, Recercat. Dipósit de la Recerca de Catalunya, instname, Recercat: Dipósit de la Recerca de Catalunya, Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)
- Publication Year :
- 2019
-
Abstract
- 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.
- Subjects :
- 2H-NbSe₂
Charge density waves
STM
DFT calculations
Transition metal dichalcogenides
Subjects
Details
- Database :
- OpenAIRE
- Journal :
- Dipòsit Digital de Documents de la UAB, Universitat Autònoma de Barcelona, Recercat. Dipósit de la Recerca de Catalunya, instname, Recercat: Dipósit de la Recerca de Catalunya, Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)
- Accession number :
- edsair.dedup.wf.001..4b10109c6f497e8fa5dd7cba709bf083