Band-edge Exciton States in a Single-walled Carbon Nanotube Revealed by Magneto-optical Spectroscopy in Ultra-high Magnetic Field

TL;DR

This study uses ultra-high magnetic field magneto-optical spectroscopy to reveal the unique ordering and energy splitting of excitonic states in single-walled carbon nanotubes, showing contrasting behaviors between the first and second sub-bands.

Contribution

It uncovers the inverse ordering of bright and dark excitonic states in different sub-bands of single-walled carbon nanotubes using high magnetic fields.

Findings

Dark exciton lies below bright exciton in the first sub-band.

Dark exciton has higher energy than bright in the second sub-band.

Distinctive Aharonov-Bohm splitting observed up to 190 T.

Abstract

We report high field magneto-optical study on the first and second sub-band transitions of single-chirality single-walled carbon nanotubes. The ordering and relative energy splitting between bright and dark excitonic states were found to be inverse between the first and second subbands. We verified that the zero-momentum dark singlet exciton lies below the bright exciton for the first subband transitions, while for the second sub-band transitions, it was found to have higher energy than the bright excitonic state. Effect of this peculiar excitonic structure was found to manifest itself in distinctive Aharonov-Bohm splitting in ultra-high magnetic fields up to 190 T.