Signatures of the Current Blockade Instability in Suspended Carbon Nanotubes

TL;DR

This paper investigates the mechanical signatures of current blockade instability in suspended carbon nanotubes, revealing observable spectral and dynamical changes that signal the transition driven by electro-mechanical coupling.

Contribution

It introduces a method to detect the current blockade transition through mechanical response measurements rather than direct current observation.

Findings

Spectral function peak broadens and shifts at low frequencies near transition

Oscillator dephasing time shortens at the transition

Non-linear effects dominate the dynamics at the transition

Abstract

Transport measurements allow sensitive detection of nanomechanical motion of suspended carbon nanotubes. It has been predicted that when the electro-mechanical coupling is sufficiently large a bistability with a current blockade appears. Unambiguous observation of this transition by current measurements may be difficult. Instead, we investigate the mechanical response of the system, namely the displacement spectral function; the linear response to a driving; and the ring-down behavior. We find that by increasing the electro-mechanical coupling the peak in the spectral function broadens and shifts at low frequencies while the oscillator dephasing time shortens. These effects are maximum at the transition where non-linearities dominate the dynamics. These strong signatures open the way to detect the blockade transition in devices currently studied by several groups.