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arXiv · 2310.08906

Controlling Umklapp scattering in bilayer graphene moir'e superlattice

Mohit Kumar Jat·Shubhankar Mishra·Harsimran Kaur Mann·Robin Bajaj·Kenji Watanabe·Takashi Taniguchi·H. R. Krishnamurthy·Manish Jain·Aveek Bid
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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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Mohit Kumar Jat, Shubhankar Mishra, Harsimran Kaur Mann, Robin Bajaj, Kenji Watanabe, Takashi Taniguchi, H. R. Krishnamurthy, Manish Jain, Aveek Bid. 2023-10-13. Controlling Umklapp scattering in bilayer graphene moir'e superlattice. https://doi.org/10.1021/acs.nanolett.3c04223

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