Interplay of electronic crystals with integer and fractional Chern insulators in moiré pentalayer graphene

Abstract

The rapid development of moiré quantum matter has recently led to the remarkable discovery of the fractional quantum anomalous Hall effect, and sparked predictions of other novel correlation-driven topological states. Here, we investigate the interplay of electronic crystals with integer and fractional Chern insulators in a moiré lattice of rhomobohedral pentalayer graphene (RPG) aligned with hexagonal boron nitride. At a doping of one electron per moiré unit cell, we see a correlated insulator with a Chern number that can be tuned between $C=0$ and $+1$ by an electric displacement field, accompanied by an array of other such insulators formed at fractional band fillings, $\nu$. Collectively, these states likely correspond to trivial and topological electronic crystals, some of which spontaneously break the discrete translational symmetry of the moiré lattice. Upon applying a modest magnetic field, a narrow region forms around $\nu =2/3$ in which transport measurements imply the emergence of a fractional Chern insulator, along with hints of weaker states at other fractional $\nu$. In the same sample, we also see a unique sequence of incipient Chern insulators arising over a broad range of incommensurate band filling near two holes per moiré unit cell. Our results establish moiré RPG as a fertile platform for studying the competition and potential intertwining of electronic crystallization and topological charge fractionalization.

8 pages, 4 figures, extended data, 10 extended data figures, 13 supplementary information figures

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Cited by in corpus (16)

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• Broken Symmetry in Ideal Chern Bands
• Berry Phase Dynamics of Sliding Electron Crystals
• Impurity-induced thermal crossover in fractional Chern insulators
• Multi-Band Exact Diagonalization and an Iteration Approach to Hunt For Fractional Chern Insulators in Rhombohedral Multilayer Graphene
• Quantum anomalous Hall effects and emergent $\mathrm{SU}(2)$ Hall ferromagnets at fractional filling of helical trilayer graphene
• Family of Aperiodic Tilings with Tunable Quantum Geometric Tensor
• Generic integer and fractional quantum anomalous Hall crystals from interaction-driven band folding
• Ideal quantum geometry of the surface states of rhombohedral graphite and its effects on the surface superconductivity
• Pairing around a Single Dirac Point: A Unifying View of Kohn-Luttinger Superconductivity in Chern Bands, Quarter Metals, and Topological Surface States
• Elastic Response and Instabilities of Anomalous Hall Crystals
• Extended Haldane Model in The Dice Lattice: Multiple Flat-Band-Induced topological Transitions Revealed
• Topological Order Without Band Topology in Moiré Graphene
• Robustness of real-space topology in moiré systems
• Spin-triplet paired Wigner crystal stabilized by quantum geometry
• Elementary Excitations, Melting Temperature, and Correlation Energy in Wigner Crystals