Electron-phonon coupling in quasi free-standing graphene

TL;DR

This study compares electron-phonon coupling in two types of quasi free-standing graphene, finding weak coupling constants around 0.05, regardless of the intercalation method or substrate, indicating similar many-body effects.

Contribution

It provides a comparative analysis of electron-phonon coupling in hydrogen- and oxygen-intercalated graphene, showing weak and similar coupling constants across different systems.

Findings

Weak electron-phonon coupling constant (~0.05) in both systems

Similar self-energy behavior observed in both types of graphene

Decoupling methods do not significantly alter many-body effects

Abstract

Quasi free-standing monolayer graphene can be produced by intercalating species like oxygen or hydrogen between epitaxial graphene and the substrate crystal. If the graphene is indeed decoupled from the substrate, one would expect the observation of a similar electronic dispersion and many-body effects, irrespective of the substrate and the material used to achieve the decoupling. Here we investigate the electron-phonon coupling in two different types of quasi free-standing monolayer graphene: decoupled from SiC via hydrogen intercalation and decoupled from Ir via oxygen intercalation. Both systems show a similar overall behaviour of the self-energy and a weak renormalization of the bands near the Fermi energy. The electron-phonon coupling is found to be sufficiently weak to make the precise determination of the coupling constant lambda through renormalization difficult. The estimated value of lambda is 0.05(3) for both systems.