Excitonic absorption signatures of twisted bilayer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">WSe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> by electron energy-loss spectroscopy
Steffi Y. Woo, Alberto Zobelli, Robert Schneider, Ashish Arora, Johann A. Preuß, Benjamin J. Carey, Steffen Michaelis de Vasconcellos, Maurizia Palummo, Rudolf Bratschitsch, Luiz H. G. Tizei
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.