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arXiv · 2502.16551

Anomalous enhancement of large-momentum scattering by electron-electron interaction in moir\'e superlattices

Taiki Sato·Hiroaki Ishizuka
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Abstract

Using a microscopic model, we show that the electron-electron interaction of flat bands deviates significantly from the Coulomb interaction. In particular, we find that large-momentum scattering is enhanced at $\theta\lesssim4^\circ$, with a non-monotonic momentum dependence appearing near the magic angle. For $\theta \gtrsim 1.2^\circ$, the enhanced large-momentum scattering can be attributed to the compact Wannier function. On the other hand, for $\theta\lesssim1.2^\circ$, the nonmonotonic momentum dependence of the interaction matrix cannot be explained by a simple Wannier orbital, indicating a nontrivial modification to the el-el interaction. Notably, the range of angles $\theta$ where the large-momentum scattering is enhanced differs from the magic angles at which nearly-flat bands emerge, suggesting that the angle dependence of material properties provides information about the effect of interaction. The results highlight unusual features of the interaction in moir\'e graphene.

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Taiki Sato, Hiroaki Ishizuka. 2025-02-23. Anomalous enhancement of large-momentum scattering by electron-electron interaction in moir\'e superlattices. https://doi.org/10.1103/7jp9-t481

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