Robust charge-density wave strengthened by electron correlations in monolayer 1T-TaSe2 and 1T-NbSe2

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-TaS2 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 TCDW-Mott, whereas this was difficult for bulk TMDs with TCDW-Mott < 200 K. Here we report a strong-coupling 2D CDW-Mott phase with a transition temperature onset of ~530 K in monolayer 1T-TaSe2. 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 TaSe2 compared to NbSe2, 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.

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• Doped Mott phase and charge correlations in monolayer 1T-NbSe${}_2$
• Spectroscopic evidence for possible quantum spin liquid behavior in a two-dimensional Mott insulator
• Nature of metallic and insulating domains in the CDW system 1T-TaSe2
• Orbital textures and evolution of correlated insulating state in monolayer 1T phase transition metal dichalcogenides
• In-situ topotactic chemical reaction for spectroscopies
• Theoretical prediction of Structural Stability and Superconductivity in Janus Ti2CSH MXene
• Emergent Quantum Phenomena of Noncentrosymmetric Charge-Density Wave in 1T-Transition Metal Dichalcogenides
• Spin-charge correlations in finite one-dimensional multi-band Fermi systems
• Electronic inhomogeneity in Cs- and Sb-terminated surfaces of CsV${}_3$Sb${}_5$ probed by scanning photoemission spectromicroscopy
• Nanoscale Modulation of Flat Bands via Controllable Charge-Density-Waves Defects in 4Hb-TaS2
• Kondo-Peierls transition with nonsymmorphic zone boundary gap formation
• Unusual temperature dependence of the band structure associated with local atomic distortion in monolayer 1T'-WTe2
• Emergent quantum phenomena in two-dimensional 1T-TaS2