Bulk and Edge Properties of Twisted Double-Bilayer Graphene
arXiv:2101.03621 · doi:10.1038/s41567-021-01419-5
Abstract
The emergence of controlled, two-dimensional moiré materials has uncovered a new platform for investigating topological physics. Twisted double bilayer graphene (TDBG) has been predicted to host a topologically non-trivial gapped phase with Chern number equal to two at charge neutrality, when half the flat bands are filled. However, it can be difficult to diagnose topological states using a single measurement because it is ideal to probe the bulk and edge properties at the same time. Here, we report a combination of chemical potential measurements, transport measurements, and theoretical calculations that show that twisted double bilayer graphene can host metallic edge transport while simultaneously being insulating in the bulk. A Landauer-Buttiker analysis of measurements on multi-terminal samples allows us to quantitatively assess edge state scattering. We interpret these results as signatures of the predicted topological phase at charge neutrality.
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Cited by in corpus (15)
- Tunable moiré materials for probing Berry physics and topology
- Nonlinear anomalous Hall effects probe topological phase-transitions in twisted double bilayer graphene
- Spontaneous time-reversal symmetry breaking in twisted double bilayer graphene
- Observation of linear and nonlinear light localization at the edges of moiré lattices
- Signature of Correlated Insulator in Electric Field Controlled Superlattice
- Symmetry-broken Chern insulators in twisted double bilayer graphene
- Direct observation of moiré flat-band breakdown at the edge of magic-angle twisted bilayer graphene
- Quantum anomalous Hall crystals in moiré bands with higher Chern number
- Ferroelectricity in twisted double bilayer graphene
- Absence of Edge States in The Valley Chern Insulator in Moiré Graphene
- Independently Tunable Flat Bands and Correlations in a Graphene Double Moiré System
- Quantum geometric moment encodes stacking order of moiré matter
- Second-Order Conductivity Probes a Cascade of Singularities in a Moiré Superlattice
- Shift current response in twisted double bilayer graphenes
- Second-Order Synaptic Memory using Inherent Plasticity of Moiré Superlattices