Emergent Symmetry and Valley Chern Insulator in Twisted Double-Bilayer Graphene
arXiv:2006.14000 · doi:10.1103/PhysRevLett.133.246401
Abstract
Theoretical calculations show that twisted double bilayer graphene (TDBG) under a transverse electric field develops a valley Chern number 2 at charge neutrality. Using thermodynamic and thermal activation measurements we report the experimental observation of a universal closing of the charge neutrality gap in the Hofstadter spectrum of TDBG at 1/2 magnetic flux per unit cell, in agreement with theoretical predictions for a valley Chern number 2 gap. Our theoretical analysis of the experimental data shows that the interaction energy, while larger than the flat-band bandwidth in TDBG near 1°does not alter the emergent valley symmetry or the single-particle band topology.
arXiv comment6 pages, 4 figures, includes supplemental material
References in corpus (45)
- The Raman Fingerprint of Graphene
- Magic-angle graphene superlattices: a new platform for unconventional superconductivity
- Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
- Boron nitride substrates for high-quality graphene electronics
- Quantum Spin Hall Insulator State in HgTe Quantum Wells
- Correlated Insulator Behaviour at Half-Filling in Magic Angle Graphene Superlattices
- Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
- Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
- Moire bands in twisted double-layer graphene
- Tuning superconductivity in twisted bilayer graphene
- Emergent ferromagnetism near three-quarters filling in twisted bilayer graphene
- Superconductors, Orbital Magnets, and Correlated States in Magic Angle Bilayer Graphene
- Intrinsic quantized anomalous Hall effect in a moiré heterostructure
- Tunable Phase Boundaries and Ultra-Strong Coupling Superconductivity in Mirror Symmetric Magic-Angle Trilayer Graphene
- Experimental demonstration of the topological surface states protected by the time-reversal symmetry
- Tunable Correlated Chern Insulator and Ferromagnetism in Trilayer Graphene/Boron Nitride Moiré Superlattice
- Signatures of Fractional Quantum Anomalous Hall States in Twisted MoTe2 Bilayer
- Electric Field Tunable Correlated States and Magnetic Phase Transitions in Twisted Bilayer-Bilayer Graphene
- Signatures of Gate-Tunable Superconductivity in Trilayer Graphene/Boron Nitride Moiré Superlattice
- Spin-polarized Correlated Insulator and Superconductor in Twisted Double Bilayer Graphene
- Evidence of Gate-Tunable Mott Insulator in Trilayer Graphene-Boron Nitride Moiré Superlattice
- Fractional Chern insulators in magic-angle twisted bilayer graphene
- Correlated states in twisted double bilayer graphene
- Integer and fractional Chern insulators in twisted bilayer MoTe2
- Electric field tunable unconventional superconductivity in alternating twist magic-angle trilayer graphene
- Strongly Correlated Chern Insulators in Magic-Angle Twisted Bilayer Graphene
- Nearly Flat Chern Bands in Moiré Superlattices
- Observation of integer and fractional quantum anomalous Hall effects in twisted bilayer MoTe2
- Correlated Insulating States in Twisted Double Bilayer Graphene
- Quantum valley Hall effect, orbital magnetism, and anomalous Hall effect in twisted multilayer graphene systems
- Hofstadter subband ferromagnetism and symmetry broken Chern insulators in twisted bilayer graphene
- Tunable correlation-driven symmetry breaking in twisted double bilayer graphene
- Moire Butterflies
- Theory of correlated insulating behaviour and spin-triplet superconductivity in twisted double bilayer graphene
- Flatbands in twisted double bilayer graphene
- Band structure and topological property of twisted double bilayer graphenes
- Gate-Tunable Topological Flat Bands in Trilayer Graphene-Boron Nitride Moiré Superlattices
- The Landau Level of Fragile Topology
- Hofstadter Topology: Non-crystalline Topological Materials at High Flux
- Correlated Hofstadter Spectrum and Flavor Phase Diagram in Magic Angle Graphene
- Hofstadter butterfly and the quantum Hall effect in twisted double bilayer graphenes
- High quality electrostatically defined hall bars in monolayer graphene
- Bulk and Edge Properties of Twisted Double-Bilayer Graphene
- Landau Levels as a Probe for Band Topology in Graphene Moiré Superlattices
- Open Momentum Space Method for Hofstadter Butterfly and the Quantized Lorentz Susceptibility