Topological electronic crystals in twisted bilayer-trilayer graphene

Abstract

In a dilute two-dimensional electron gas, Coulomb interactions can stabilize the formation of a Wigner crystal. Although Wigner crystals are topologically trivial, it has been predicted that electrons in a partially-filled band can break continuous translational symmetry and time-reversal symmetry spontaneously to form a form of topological electron crystal known as an anomalous Hall crystal. Here, we report the observation of a generalized version of the anomalous Hall crystal in twisted bilayer-trilayer graphene, whose formation is driven by the moire potential. The crystal forms at a band filling factor of one electron per four moiré unit cells ($\nu =1/4$) and quadruples the unit-cell area, coinciding with an integer quantum anomalous Hall effect. The Chern number of the state is exceptionally tunable, and can be switched reversibly between $+1$ and $-1$ by electric and magnetic fields. Several other topological electronic crystals arise in a modest magnetic field, originating from $\nu =1/3$, $1/2$, $2/3$, and $3/2$. The quantum geometry of the folded bands is likely very different from that of the original parent band, enabling possible future discoveries of correlation-driven topological phenomena

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Cited by in corpus (17)

• Superconductivity and quantized anomalous Hall in rhombohedral graphene
• Interplay of electronic crystals with integer and fractional Chern insulators in moiré pentalayer graphene
• Quantum anomalous Hall crystals in moiré bands with higher Chern number
• Broken Symmetry in Ideal Chern Bands
• Fractional Chern Insulator and Quantum Anomalous Hall Crystal in Twisted MoTe${}_2$
• Chern-Textured Exciton Insulators with Valley Spiral Order in Moiré Materials
• Fractional Chern insulator states in an isolated flat band of zero Chern number
• Quantum anomalous Hall effects and emergent $\mathrm{SU}(2)$ Hall ferromagnets at fractional filling of helical trilayer graphene
• Electronic Crystal Phases in the Presence of Non-Uniform Berry Curvature and Tunable Berry Flux: The ${\lambda }_N$-Jellium model
• Generic integer and fractional quantum anomalous Hall crystals from interaction-driven band folding
• Review of the tight-binding method applicable to the properties of moiré superlattices
• Designing (higher) Hall crystals
• Giant Shift Current in Electrically-Tunable Superlattice Bilayer Graphene
• Emergent electronic insulating states in a one-dimensional moiré superlattice
• Topological Order Without Band Topology in Moiré Graphene
• Continuous transition and gapless roton inside fractional quantum anomalous Hall states
• Spin-triplet paired Wigner crystal stabilized by quantum geometry