Controlling Umklapp scattering in bilayer graphene moir'e superlattice

Abstract

In this Letter, we present experimental findings on electron-electron scattering in a two-dimensional moir'e heterostructure with tunable Fermi wave vector, reciprocal lattice vector, and band gap. We achieve this in high-mobility aligned heterostructures of bilayer graphene (BLG) and hBN. Around half-filling, the primary contribution to the resistance of BLG/hBN aligned superlattices arises from electron-electron Umklapp (Uee) scattering, making the resistance of graphene/hBN moir'e devices significantly larger than that of non-aligned devices (where Uee is forbidden). We quantify the strength of the Uee scattering and find that it follows a universal scaling with Fermi energy and has a non-monotonic dependence on the charge carrier density. The Uee scattering is strongly electric field tunable and affected by layer-polarization of BLG. It has a strong particle-hole asymmetry - the resistance when the chemical potential is in the conduction band is significantly lesser than when it is in the valence band, making the electron-doped regime more practical for potential applications.

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Cited by in corpus (4)

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• Electric field tunable bands in doubly aligned bilayer graphene hBN moire superlattice
• Hexagonal boron nitride/bilayer graphene moiré superlattices in the Dirac-material family: energy-band engineering and carrier doping by dual gating
• Coexisting Massive and Massless Dirac Fermions in Moire'-Reconstructed Bilayer Graphene