Effects of Lithium Intercalation in Twisted Bilayer Graphene

TL;DR

This study uses first-principles calculations to explore how lithium intercalation affects the electronic properties of twisted bilayer graphene, revealing clustering behavior and tunable band structure modifications.

Contribution

It introduces a detailed analysis of lithium intercalation effects in twisted bilayer graphene, highlighting potential for spatial control and property tuning in moiré systems.

Findings

Li clusters in AA regions at low concentration

Intercalation modifies band structure via interlayer coupling

Potential for tuning moiré physics and applications

Abstract

We investigate the effects of lithium intercalation in twisted bilayers of graphene, using first-principles electronic structure calculations. To model this system we employ commensurate supercells that correspond to twist angles of 7.34$^\circ$ and 2.45$^\circ$. From the energetics of lithium absorption we demonstrate that for low Li concentration the intercalants cluster in the AA regions with double the density of a uniform distribution. The charge donated by the Li atoms to the graphene layers results in modifications to the band structure that can be qualitatively captured using a continuum model with modified interlayer couplings in a region of parameter space that has yet to be explored either experimentally or theoretically. Thus, the combination of intercalation and twisted layers simultaneously provides the means for spatial control over material properties and an additional knob with which to tune moir\'e physics in twisted bilayers of graphene, with potential applications ranging from energy storage and conversion to quantum information.