Experimental evidence of plasmarons and effective fine structure constant in electron-doped graphene/h-BN heterostructure

Electron-electron interaction is fundamental in condensed matter physics and can lead to composite quasiparticles called plasmarons, which strongly renormalize the dispersion carry information of electron-electron coupling strength as defined by effective fine structure constant $\alpha_{ee}^*$. Although h-BN with unique dielectric properties has been widely used an important substrate for graphene, so far there no experimental report plasmarons graphene/h-BN yet. Here, we direct observation plasmaron heterostructures through angle-resolved photoemission spectroscopy (ARPES) measurements upon {\it situ} electron doping. Characteristic diamond-shaped observed near Dirac cone both 0$^\circ$ (aligned) 13.5$^\circ$ (twisted) graphene/h-BN, $\alpha_{ee}^*$ extracted be $\alpha_{ee}^*\approx0.9\pm 0.1$, highlighting role interaction. Our results suggest ideal platform investigating strong weak screening, lays gate-tunable nano-electronics nano-plasmonics.