Imaging local discharge cascades for correlated electrons in WS2/WSe2 moiré superlattices
arXiv:2102.09986 · doi:10.1038/s41567-021-01324-x
Abstract
Transition metal dichalcogenide (TMD) moiré heterostructures provide an ideal platform to explore the extended Hubbard model1 where long-range Coulomb interactions play a critical role in determining strongly correlated electron states. This has led to experimental observations of Mott insulator states at half filling2-4 as well as a variety of extended Wigner crystal states at different fractional fillings5-9. Microscopic understanding of these emerging quantum phases, however, is still lacking. Here we describe a novel scanning tunneling microscopy (STM) technique for local sensing and manipulation of correlated electrons in a gated WS2/WSe2 moiré superlattice that enables experimental extraction of fundamental extended Hubbard model parameters. We demonstrate that the charge state of local moiré sites can be imaged by their influence on STM tunneling current, analogous to the charge-sensing mechanism in a single-electron transistor. In addition to imaging, we are also able to manipulate the charge state of correlated electrons. Discharge cascades of correlated electrons in the moiré superlattice are locally induced by ramping the STM bias, thus enabling the nearest-neighbor Coulomb interaction (UNN) to be estimated. 2D mapping of the moiré electron charge states also enables us to determine onsite energy fluctuations at different moiré sites. Our technique should be broadly applicable to many semiconductor moiré systems, offering a powerful new tool for microscopic characterization and control of strongly correlated states in moiré superlattices.
References in corpus (22)
- The SIESTA method for ab initio order-N materials simulation
- Efficient index handling of multidimensional periodic boundary conditions
- Correlated Insulator Behaviour at Half-Filling in Magic Angle Graphene Superlattices
- Superconductors, Orbital Magnets, and Correlated States in Magic Angle Bilayer Graphene
- Optical detection of Mott and generalized Wigner crystal states in WSe2/WS2 moiré superlattices
- Magic continuum in twisted bilayer WSe2
- Hubbard model physics in transition metal dichalcogenide moiré bands
- Electric Field Tunable Correlated States and Magnetic Phase Transitions in Twisted Bilayer-Bilayer Graphene
- Abundance of correlated insulating states at fractional fillings of WSe/WS moiré superlattices
- Spin-polarized Correlated Insulator and Superconductor in Twisted Double Bilayer Graphene
- Evidence of Gate-Tunable Mott Insulator in Trilayer Graphene-Boron Nitride Moiré Superlattice
- Cascade of Phase Transitions and Dirac Revivals in Magic Angle Graphene
- Moiré superlattice in a MoSe/hBN/MoSe heterostructure: from coherent coupling of inter- and intra-layer excitons to correlated Mott-like states of electrons
- Correlated Insulating States at Fractional Fillings of the WS2/WSe2 Moiré Lattice
- Gate-Controlled Ionization and Screening of Cobalt Adatoms on a Graphene Surface
- Stripe phases in WSe2/WS2 moiré superlattices
- Probing critical point energies of transition metal dichalcogenides: surprising indirect gap of single layer
- Imaging moiré flat bands in 3D reconstructed WSe2/WS2 superlattices
- Moiré quantum chemistry: charge transfer in transition metal dichalcogenide superlattices
- Evolution of Microscopic Localization in Graphene in a Magnetic Field from Scattering Resonances to Quantum Dots
- Charge Transfer Excitations, Pair Density Waves, and Superconductivity in Moiré Materials
- Nanoscale Conductivity Imaging of Correlated Electronic States in WSe2/WS2 Moiré Superlattices