Charge order with unusual star-of-David lattice in monolayer NbTe2

Abstract

Interplay between fermiology and electron correlation is crucial for realizing exotic quantum phases. Transition-metal dichalcogenide (TMD) 1T-TaS2 has sparked a tremendous attention owing to its unique Mott-insulating phase coexisting with the charge-density wave (CDW). However, how the fermiology and electron correlation are associated with such properties has yet to be claried. Here we demonstrate that monolayer 1T-NbTe2 is a new class of two-dimensional TMD which has the star-of-David lattice similarly to bulk TaS2 and isostructural monolayer NbSe2, but exhibits a metallic ground state with an unusual lattice periodicity root19xroot19 characterized by the sparsely occupied star-of-David lattice. By using angle-resolved photoemission and scanning-tunneling spectroscopies in combination with first-principles band-structure calculations, we found that the hidden Fermi-surface nesting and associated CDW formation are a primary cause to realize this unique correlated metallic state with no signature of Mott gap. The present result points to a vital role of underlying fermiology to characterize the Mott phase of TMDs.

To be published in Physical Review B

References in corpus (8)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Discovery of unconventional chiral charge order in kagome superconductor KV3Sb5
• Fermi surface nesting and the origin of Charge Density Waves in metals
• A quantum phase transition from triangular to stripe charge order in NbSe${}_2$
• Band insulator to Mott insulator transition in 1T-TaS${}_2$
• Direct identification of Mott Hubbard band pattern beyond charge density wave superlattice in monolayer 1T-NbSe2
• Correlated electronic states at domain walls of a Mott-charge-density-wave insulator 1T-TaS2
• Electronic states of multilayer VTe2: quasi-one-dimensional Fermi surface and implications to charge-density waves

Cited by in corpus (4)

• Realization of multiple charge density waves in NbTe2 at the monolayer limit
• Electronic Landscape of Group-5 Transition Metal Ditellurides $M$Te${}_2$ ($M$ = V, Nb, Ta): Multiple Crystal Phases with Local Bonds and Flat Bands
• The rich structural, electronic and bonding landscape of 1$T$-type TaTe${}_2$ single-layers
• Observation of momentum dependent charge density wave gap in EuTe4