Diameter-dependent conductance oscillations in carbon nanotubes upon torsion

TL;DR

This study combines experiments and ab initio calculations to clarify how torsion affects conductance oscillations in carbon nanotubes, revealing a diameter-dependent behavior consistent with single-wall nanotube physics.

Contribution

It demonstrates that torsion-induced conductance oscillations depend on diameter and are due to Fermi momentum shifts, not inter-wall registry changes.

Findings

Oscillation period inversely proportional to squared diameter

Differential torsion decouples nanotube walls near Fermi level

Fermi momentum shifts cause conductance oscillations

Abstract

We combine electromechanical measurements with {\em ab initio} density functional calculations to settle the controversy about the origin of torsion-induced conductance oscillations in multi-wall carbon nanotubes. According to our observations, the oscillation period is inversely proportional to the squared diameter of the nanotube, as expected for a single-wall nanotube of the same diameter. This is supported by our theoretical finding that differential torsion effectively decouples the walls of a multi-wall nanotube near the Fermi level and moves the Fermi momentum across quantization lines. We exclude the alternative explanation linked to registry changes between the walls, since it would cause a different diameter dependence of the oscillation period.