Strong interfacial charge transfer from CrSBr induces extreme hole doping and quantum-Hall states in graphene heterostructures

Abstract

Magnetic van der Waals (vdW) semiconductors offer unique opportunities to integrate spin and charge degrees of freedom in atomically thin devices. Here, we fabricate dual-gated heterostructures consisting of exfoliated CrSBr, stacked beneath monolayer graphene and encapsulated by hexagonal boron nitride (h-BN). Magnetotransport measurements performed at temperatures down to 2 K and magnetic fields up to 13.5 T demonstrate that CrSBr acts as an exceptionally strong p-type doping source to graphene in this vdW heterostructure, driving the graphene Fermi level deep into the valence band with hole density reaching ~10¹³ cm⁻². High-frequency Shubnikov-de Haas oscillations and well-quantized quantum Hall plateaus were observed, confirming the high quality of the doped graphene channel. Furthermore, nearly field-independent resistance ridges emerged at a top gate bias of ≈ −3 V, which we attribute to graphene/h-BN moiré minibands with a twist angle of >3°. These miniband features become experimentally accessible solely due to the extreme p-doping by CrSBr, a regime that is inaccessible via conventional gating techniques.

Keywords

2d materials / heterostructure / moirésuperlattices / p-doping / quantum Hall effects

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