Intersubband Edge Singularity in Metallic Nanotubes

TL;DR

This paper investigates how many-body interactions in metallic carbon nanotubes influence optical absorption, revealing an enhancement and power-law behavior in absorption probability due to electron-electron interactions.

Contribution

It demonstrates that many-body effects enhance optical absorption between gapless and gapped states, contrary to their suppressive effect on the density of states.

Findings

Optical absorption is enhanced by many-body effects.

Absorption probability follows a power-law frequency dependence with an exponent of -0.2.

Electron-electron interactions suppress the density of states but enhance optical absorption.

Abstract

Tunneling density of states of both the massless and massive (gapped) particles in metallic carbon nanotubes is known to have anomalous energy dependence. This is the result of coupling to multiple low-energy bosonic excitation (plasmons). For both kinds of particles the ensuing effect is the suppression of the density of states by electron-electron interactions. We demonstrate that the optical absorption between gapless and gapped states is affected by the many-body effects in the opposite way. The absorption probability is enhanced compared with the non-interacting value and develops a power-law frequency dependence with the exponent -0.2 for typical nanotubes.