Excitonic absorption signatures of twisted bilayer WSe2 by electron energy-loss spectroscopy

Abstract

The excitonic response in twisted bilayer WSe${}_{2}$ as a function of the moir\'e angle has been investigated using electron energy loss spectroscopy under cryogenic conditions, and interpreted on the basis of first-principles calculations of the dielectric response of the $A\phantom{\rule{0}{0ex}}A\ensuremath{'}$ stacked bilayer WSe${}_{2}$ relative to monolayer WSe${}_{2}$. This work provides valuable insight into the physical origins of high-energy absorption resonances in twisted bilayers, where the tuning of the excitonic peak $C$ transitions is an effective indicator of the interlayer coupling.