2025/02/23 by Sato, Taiki, Ishizuka, Hiroaki · 1 citation
#FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
paper · doi:10.48550/arxiv.2502.16551
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 θ\lesssim4^∘, with a non-monotonic momentum dependence appearing near the magic angle. For θ\gtrsim 1.2^∘, the enhanced large-momentum scattering can be attributed to the compact Wannier function. On the other hand, for θ\lesssim1.2^∘, 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 θ 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 moiré graphene.