Thermal Einstein-de Haas Effect Induced by Chiral Phonons in Carbon Nanotubes

TL;DR

This paper predicts that chiral carbon nanotubes can undergo thermally induced rotation due to phonon angular momentum, revealing a thermal Einstein-de Haas effect driven by chiral phonons.

Contribution

It introduces the concept of phonon angular momentum in chiral nanotubes and predicts a thermal Einstein-de Haas effect caused by chiral phonons.

Findings

Degenerate phonon modes split in chiral SWCNTs

Chiral SWCNTs exhibit finite phonon angular momentum

Thermally induced rotation is predicted in chiral nanotubes

Abstract

We investigate the effects of chirality on phonon thermal transport in semiconducting chiral single-walled carbon nanotubes (SWCNTs) using lattice dynamics combined with Boltzmann transport theory. We find that transverse acoustic and optical phonon modes, which are degenerate in nonchiral zigzag and armchair SWCNTs, are split in chiral SWCNTs, giving rise to finite phonon angular momentum associated with circular motion of individual atoms. This angular momentum is most efficiently generated in small-diameter nanotubes with intermediate chiral angles. Consequently, chiral SWCNTs are predicted to undergo thermally induced rigid-body rotation with an experimentally observable angular velocity via the thermal Einstein-de Haas effect.