Observation of flat $\Gamma$ moiré bands in twisted bilayer WSe${}_2$

Abstract

The recent observation of correlated phases in transition metal dichalcogenide moiré systems at integer and fractional filling promises new insight into metal-insulator transitions and the unusual states of matter that can emerge near such transitions. Here, we combine real- and momentum-space mapping techniques to study moiré superlattice effects in 57.4${}^{\circ }$ twisted WSe${}_2$ (tWSe${}_2$). Our data reveal a split-off flat band that derives from the monolayer $\Gamma$ states. Using advanced data analysis, we directly quantify the moiré potential from our data. We further demonstrate that the global valence band maximum in tWSe${}_2$ is close in energy to this flat band but derives from the monolayer K-states which show weaker superlattice effects. These results constrain theoretical models and open the perspective that $\Gamma$-valley flat bands might be involved in the correlated physics of twisted WSe${}_2$.

References in corpus (10)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Advanced capabilities for materials modelling with Quantum ESPRESSO
• van der Waals forces in density functional theory: The vdW-DF method
• Magic in twisted transition metal dichalcogenide bilayers
• Quantum Criticality in Twisted Transition Metal Dichalcogenides
• Quantum critical behavior in magic-angle twisted bilayer graphene
• First-principles theory of field-effect doping in transition-metal dichalcogenides: Structural properties, electronic structure, Hall coefficient, and electrical conductivity
• Tunable bilayer Hubbard model physics in twisted WSe2
• Correlated interlayer exciton insulator in double layers of monolayer WSe2 and moiré WS2/WSe2
• Multifaceted moiré superlattice physics in twisted WSe${}_2$ bilayers

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• Evolution of flat bands in MoSe${}_2$/WSe${}_2$ moiré lattices: A study combining machine learning and band unfolding methods
• Probing excitons with time-resolved momentum microscopy
• Atomically-Thin Transition Metal Dichalcogenide Nanolasers: Challenges and Opportunities
• Pressure-tuned many-body phases through $\Gamma$-K valleytronics in moiré bilayer WSe${}_2$
• Dirac quantum criticality in twisted double bilayer transition metal dichalcogenides
• Visualizing Electronic Structure of Twisted Bilayer MoTe2 in Devices
• Signatures of superconducting pairing driven by electron-electron interactions in moiré WSe${}_2$/WSe${}_2$ homobilayer modelled by Hubbard Hamiltonian
• Spin-orbital magnetism in moiré Wigner molecules
• Interplay of Rashba spin-orbit coupling and Coulomb interaction in topological spin-triplet excitonic condensates
• Interaction enhanced inter-site hoppings for holons and interlayer exciton insulators in moiré correlated insulators