Metallic screening and correlation effects in superconducting fullerenes

TL;DR

This paper analyzes how frequency-dependent Coulomb interactions in alkali-doped C60 influence electron pairing, revealing that screening effects can reduce repulsion and potentially induce effective attraction, impacting superconductivity.

Contribution

It provides a detailed calculation of effective electron interactions in fullerene superconductors considering frequency dependence, highlighting the role of screening in electron pairing.

Findings

Screening significantly reduces Coulomb repulsion at the Fermi level.

Frequency dependence can lead to an effective attraction between electrons.

Long-range Coulomb effects are diminished in the considered regime.

Abstract

We consider the frequency dependent Coulomb interaction between electrons in a molecular metal in the limit in which the conduction bandwidth is much less than the plasma frequency, which in turn is much less than intramolecular excitation energies. In particular, we compute the effective interactions at the Fermi energy in alkali-doped C$_{60}$, to second order in the screened interactions. The frequency dependence of the screening substantially reduces the effects of the long-range part of the Coulomb interaction, leading to the possibility of an effective attraction between electrons.