Robust charge-density wave strengthened by electron correlations in monolayer 1T-TaSe<sub>2</sub> and 1T-NbSe<sub>2</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34620875.
- Also identified by DOI 10.1038/s41467-021-26105-1 and PMC identifier 8497551.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Combination of low-dimensionality and electron correlation is vital for exotic quantum phenomena such as the Mott-insulating phase and high-temperature superconductivity. Transition-metal dichalcogenide (TMD) 1T-TaS<sub>2</sub> has evoked great interest owing to its unique nonmagnetic Mott-insulator nature coupled with a charge-density-wave (CDW). To functionalize such a complex phase, it is essential to enhance the CDW-Mott transition temperature T<sub>CDW-Mott</sub>, whereas this was difficult for bulk TMDs with T<sub>CDW-Mott</sub> < 200 K. Here we report a strong-coupling 2D CDW-Mott phase with a transition temperature onset of ~530 K in monolayer 1T-TaSe<sub>2</sub>. Furthermore, the electron correlation derived lower Hubbard band survives under external perturbations such as carrier doping and photoexcitation, in contrast to the bulk counterpart. The enhanced Mott-Hubbard and CDW gaps for monolayer TaSe<sub>2</sub> compared to NbSe<sub>2</sub>, originating in the lattice distortion assisted by strengthened correlations and disappearance of interlayer hopping, suggest stabilization of a likely nonmagnetic CDW-Mott insulator phase well above the room temperature. The present result lays the foundation for realizing monolayer CDW-Mott insulator based devices operating at room temperature.