Expanding the moiré material library continues to reveal novel quantum phases and emergent electronic behaviors. Here we introduce ${\mathrm{PbI}}_2$ into the moiré family and investigate the magnetotransport properties of a hexagonal boron nitride/graphene/${\mathrm{PbI}}_2$ heterostructure. In the high-field quantum Hall regime, we observe robust dissipationless transport at the charge neutrality point, indicative of incompressible states at filling factor ${\nu }_h=0$. A fractional conductance plateau at $2/3,e^2/h$ emerges, which we attribute to a Chern junction formed between domains with distinct Chern numbers arising from moiré-modulated and conventional quantum Hall states. Additionally, coherent electronic interference appears along trajectories associated with the ${\nu }_m=-2$ Chern state. These observations provide compelling evidence for the formation of moiré domains that nontrivially interrupt incompressible quantum Hall states, reflecting the strong moiré potential in the BN/graphene/${\mathrm{PbI}}_2$ superlattice. We suggest that the moiré Hofstadter spectrum coupled with the proximity-induced spin-orbit interaction from ${\mathrm{PbI}}_2$ gives rise to a high magnetic field topological insulator phase explaining ballistic transport at the charge neutrality point in the graphene monolayer.

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• Mesoscopics
• Quantum Hall effect
• Graphene
• Twisted heterostructures