Direct observation of minibands in twisted heterobilayers

Abstract

Stacking two-dimensional (2D) van der Waals materials with different interlayer atomic registry in a heterobilayer causes the formation of a long-range periodic superlattice that may bestow the heterostructure with exotic properties such as new quantum fractal states [1-3] or superconductivity [4, 5]. Recent optical measurements of transition metal dichalcogenide (TMD) heterobilayers have revealed the presence of hybridized interlayer electron-hole pair excitations at energies defined by the superlattice potential [6-10]. The corresponding quasiparticle band structure, so-called minibands, have remained elusive and no such features have been reported for heterobilayers comprised of a TMD and another type of 2D material. Here, we introduce a new X-ray capillary technology for performing micro-focused angle-resolved photoemission spectroscopy (microARPES) with a spatial resolution on the order of 1 $\mu$m, enabling us to map the momentum-dependent quasiparticle dispersion of heterobilayers consisting of graphene on WS${}_2$ at variable interlayer twist angles ($\theta$). Minibands are directly observed for $\theta =2.5^{\circ }$ in multiple mini Brillouin zones (mBZs), while they are absent for a larger twist angle of $\theta =26.3^{\circ }$. These findings underline the possibility to control quantum states via the stacking configuration in 2D heterostructures, opening multiple new avenues for generating materials with enhanced functionality such as tunable electronic correlations [11] and tailored selection rules for optical transitions [12].

arXiv commentMain manuscript: 14 pages, 4 figures. Supporting information: 8 pages, 5 figures

References in corpus (26)

• Magic-angle graphene superlattices: a new platform for unconventional superconductivity
• Ultrafast Charge Transfer in Atomically Thin MoS2/WS2 Heterostructures
• Tuning superconductivity in twisted bilayer graphene
• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Hofstadter's butterfly in moire superlattices: A fractal quantum Hall effect
• Massive Dirac fermions and Hofstadter butterfly in a van der Waals heterostructure
• Direct observation of the transition from indirect to direct bandgap in atomically thin epitaxial MoSe2
• Moiré Excitons in Van der Waals Heterostructures
• Cloning of Dirac fermions in graphene superlattices
• Signatures of moiré-trapped valley excitons in MoSe${}_2$/WSe${}_2$ heterobilayers
• Observation of Moiré Excitons in WSe2/WS2 Heterostructure Superlattices
• Resonantly hybridised excitons in moiré superlattices in van der Waals heterostructures
• Hubbard model physics in transition metal dichalcogenide moiré bands
• Determination of band alignment in the single layer MoS2/WSe2 heterojunction
• Dirac Cones and Minigaps for Graphene on Ir(111)
• Momentum-space indirect interlayer excitons in transition metal dichalcogenide van der Waals heterostructures
• Second generation Dirac cones and inversion symmetry breaking induced gaps in graphene/hexagonal boron nitride
• Interlayer hybridization and moiré superlattice minibands for electrons and excitons in heterobilayers of transition-metal dichalcogenides
• Electronic Structure of Epitaxial Single-Layer MoS${}_2$
• In-plane orientation effects on the electronic structure, stability and Raman scattering of monolayer graphene on Ir(111)
• Giant spin-splitting and gap renormalization driven by trions in single-layer WS${}_2$/h-BN heterostructures
• Dynamic Spin Injection into Chemical Vapor Deposited Graphene
• Spatially Resolved Electronic Properties of Single-Layer WS${}_2$ on Transition Metal Oxides
• Electronic structure of transferred graphene/h-BN van der Waals heterostructures with nonzero stacking angles by nano-ARPES
• Dynamical spin injection at a quasi-one-dimensional ferromagnet-graphene interface
• General theoretical description of angle-resolved photoemission spectroscopy of van der Waals structures

Cited by in corpus (18)

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• Accessing the spectral function of in operando devices by angle-resolved photoemission spectroscopy
• Mixed singlet-triplet superconducting state within the moiré $t$-$J$-$U$ model as applied to the description of twisted WSe${}_2$ bilayer
• New polymorphic phase and rich phase diagram in the PdSe2-xTex system
• Moiré-induced optical non-linearities: Single and multi-photon resonances
• Enhanced Superconductivity in the Se-substituted 1T-PdTe${}_2$
• Momentum-resolved view of highly tunable many-body effects in a graphene/hBN field-effect device
• Visualizing band structure hybridization and superlattice effects in twisted MoS${}_2$/WS${}_2$ heterobilayers
• Determination of interatomic coupling between two-dimensional crystals using angle-resolved photoemission spectroscopy
• Band alignment and interlayer hybridisation in transition metal dichalcogenide/hexagonal boron nitride heterostructures
• Probing excitons with time-resolved momentum microscopy
• Revealing flat bands and hybridization gaps in a twisted bilayer graphene device with microARPES
• Photonics in Flatland: Challenges and Opportunities for Nanophotonics with 2D Semiconductors
• Autonomous microARPES
• Moiré induced electronic structure modifications in monolayer V${}_2$S${}_3$ on Au(111)
• An autoencoder for compressing angle-resolved photoemission spectroscopy data
• Visualizing Electronic Structure of Twisted Bilayer MoTe2 in Devices