Electron-Phonon Coupling in Highly-Screened Graphene

TL;DR

This study uses high-resolution photoemission spectroscopy to measure electron-phonon coupling in graphene on copper, finding agreement with theory due to substrate screening and revealing a notable bandgap at the Dirac point.

Contribution

It demonstrates that substrate screening reduces electron-electron interactions, allowing accurate comparison of electron-phonon coupling with theoretical models in graphene.

Findings

Electron-phonon interaction strength matches theoretical predictions.

Significant bandgap observed at the Dirac point.

Substrate screening simplifies electron interaction analysis.

Abstract

Photoemission studies of graphene have resulted in a long-standing controversy concerning the strength of the experimental electron-phonon interaction in comparison with theoretical calculations. Using high-resolution angle-resolved photoemission spectroscopy we study graphene grown on a copper substrate, where the metallic screening of the substrate substantially reduces the electron-electron interaction, simplifying the comparison of the electron-phonon interaction between theory and experiment. By taking the nonlinear bare bandstructure into account, we are able to show that the strength of the electron-phonon interaction does indeed agree with theoretical calculations. In addition, we observe a significant bandgap at the Dirac point of graphene.