Enhanced Many-Electron Effects on Excited States of Gated Bilayer Graphene

TL;DR

This study uses advanced first-principles simulations to accurately analyze the excited-state properties of gated bilayer graphene, revealing the critical role of many-electron effects and predicting novel excitonic phenomena.

Contribution

First-principles GW-BSE simulations provide the first accurate quasiparticle and optical spectra for gated bilayer graphene, highlighting the importance of many-electron effects.

Findings

Enhanced electron-electron interactions significantly increase the QP band gap.

Infrared absorption spectra are dominated by bright bound excitons.

Predicted exotic excitonic effects for future optoelectronic applications.

Abstract

By employing the first-principles GW-Bethe-Salpeter Equation (BSE) simulation, we obtain, for the first time, the accurate quasiparticle (QP) band gap, optical absorption spectra and their dependence on the gate field of gated bilayer graphene (GBLG). Many-electron effects are shown to be extremely important to understand these excited-state properties; enhanced electron-electron interactions dramatically enlarge the QP band gap; infrared optical absorption spectra are dictated by bright bound excitons. Our results well explain recent experiments and satisfyingly solve the puzzle about the inconsistency between experimentally measured transport and optical band gaps. Moreover, our calculation reveals fine excitonic structures and predicts exotic excitonic effects that have not been observed yet, which can be of interest for optoelectronics applications based on GBLG.