Phonon renormalisation in doped bilayer graphene

TL;DR

This study investigates how doping affects phonon behavior in bilayer graphene, revealing that the Raman G peak's shift and shape changes can measure interlayer coupling strength, advancing understanding of its electronic properties.

Contribution

It demonstrates how phonon renormalisation in doped bilayer graphene can be used to directly measure interlayer coupling strength through Raman spectroscopy.

Findings

G peak stiffens and sharpens with doping

Change in slope of G peak position indicates interlayer coupling

Provides a method to quantify interlayer interactions

Abstract

We report phonon renormalisation in bilayer graphene as a function of doping. The Raman G peak stiffens and sharpens for both electron and hole doping, as a result of the non-adiabatic Kohn anomaly at the $\Gamma$ point. The bilayer has two conduction and valence subbands, with splitting dependent on the interlayer coupling. This results in a change of slope in the variation of G peak position with doping, which allows a direct measurement of the interlayer coupling strength.