Absorption and optical selection rules of tunable excitons in biased bilayer graphene

Biased bilayer graphene, with its easily tunable band gap, presents itself as the ideal system to explore the excitonic effect in graphene-based systems. In this paper we study the excitonic optical response of such a system by combining a tight-binding model with the solution of the Bethe-Salpeter equation, the latter being solved in a semianalytical manner, requiring a single numerical quadrature, thus allowing for a transparent calculation. With our approach we start by analytically obtaining the optical selection rules, followed by the computation of the absorption spectrum for the case of a biased bilayer encapsulated in hexagonal boron nitride, a system which has been the subject of a recent experimental study. Excellent agreement is seen when we compare our theoretical prediction with the experimental data.

Automated summary

This paper explores the excitonic optical response of biased bilayer graphene using a combination of tight-binding model and the solution of the Bethe-Salpeter equation. The optical selection rules are obtained analytically, followed by the calculation of the absorption spectrum of a biased bilayer encapsulated in hexagonal boron nitride. The theoretical prediction shows excellent agreement with experimental data.