Secondary electron interference from trigonal warping in clean carbon nanotubes

TL;DR

This paper studies secondary electron interference patterns in ultraclean carbon nanotubes caused by trigonal warping of Dirac cones, revealing insights into backscattering processes and enabling estimation of the nanotube's chiral angle.

Contribution

It demonstrates the origin of secondary interference in carbon nanotubes due to trigonal warping and shows how to extract the chiral angle from conductance patterns.

Findings

Identification of secondary interference caused by trigonal warping.

Estimation of the nanotube's chiral angle from conductance data.

Observation of superstructure superimposed on Fabry-Perot oscillations.

Abstract

We investigate Fabry-Perot interference in an ultraclean carbon nanotube resonator. The conductance shows a clear superstructure superimposed onto conventional Fabry-Perot oscillations. A sliding average over the fast oscillations reveals a characteristic slow modulation of the conductance as a function of the gate voltage. We identify the origin of this secondary interference in intervalley and intravalley backscattering processes which involve wave vectors of different magnitude, reflecting the trigonal warping of the Dirac cones. As a consequence, the analysis of the secondary interference pattern allows us to estimate the chiral angle of the carbon nanotube.