Phonon dispersion and electron-phonon interaction in peanut-shaped fullerene polymers

TL;DR

This study investigates how the unique radius modulation in peanut-shaped C60 fullerene polymers affects their phonon behavior and electron-phonon interactions, with implications for low-temperature phenomena like Peierls instability.

Contribution

It introduces a continuum model to analyze phonon dispersion and electron-phonon interactions specific to peanut-shaped C60 polymers, highlighting their unique low-frequency phonon modes.

Findings

Zone-folding of phonon dispersion curves observed.

Radial breathing mode relaxes quickly due to zone-folding.

Few electron and phonon modes dominate the electron-phonon interaction.

Abstract

We reveal that the periodic radius modulation peculiar to one-dimensional (1D) peanut-shaped fullerene (C$_{60}$) polymers exerts a strong influence on their low-frequency phonon states and their interactions with mobile electrons. The continuum approximation is employed to show the zone-folding of phonon dispersion curves, which leads to fast relaxation of a radial breathing mode in the 1D C$_{60}$ polymers. We also formulate the electron-phonon interaction along the deformation potential theory, demonstrating that only a few set of electron and phonon modes yields a significant magnitude of the interaction relevant to the low-temperature physics of the system. The latter finding gives an important implication for the possible Peierls instability of the C$_{60}$ polymers suggested in the earlier experiment.