Electronic correlations in graphite and carbon nanotubes from Auger spectroscopy

TL;DR

This study measures the screened on-site Coulomb repulsion in graphite and carbon nanotubes using Auger spectroscopy and a theoretical model, revealing different interaction strengths in these carbon allotropes.

Contribution

It introduces a new theoretical analysis based on an extended Cini-Sawatzky approach with minimal fitting parameters to determine Coulomb interactions.

Findings

Screened Coulomb repulsion in graphite is 2.1 eV.

In nanotubes, it is 4.6 eV, stable across different radii.

The theoretical model accurately reproduces experimental spectra.

Abstract

We have determined the screened on-site Coulomb repulsion in graphite and single wall carbon nanotubes by measuring their Auger spectra and performing a new theoretical analysis based on an extended Cini-Sawatzky approach where only one fit parameter is employed. The experimental lineshape is very well reproduced by the theory and this allows to determine the value of the screened on-site repulsion between $2p$ states, which is found to be 2.1 eV in graphite and 4.6 eV in nanotubes. The latter is robust by varying the nanotube radius from 1 to 2 nm.