Alteration of superconductivity of suspended carbon nanotubes by deposition of organic molecules

TL;DR

This study demonstrates that coating suspended carbon nanotubes with organic polymers gradually suppresses their superconductivity, likely due to the suppression of radial breathing phonon modes essential for superconductivity.

Contribution

It reveals the role of radial breathing phonon modes in superconductivity of carbon nanotubes and shows how organic coating can modulate this property.

Findings

Superconductivity decreases with organic coating.

Normal resistance changes less than 20%.

Radial breathing modes are linked to superconductivity.

Abstract

We have altered the superconductivity of a suspended rope of single walled carbon nanotubes, by coating it with organic polymers. Upon coating, the normal state resistance of the rope changes by less than 20 percent. But superconductivity, which on the bare rope shows up as a substantial resistance decrease below 300 mK, is gradualy suppressed. We correlate this to the suppression of radial breathing modes, measured with Raman Spectroscopy on suspended Single and Double-walled carbon nanotubes. This points to the breathing phonon modes as being responsible for superconductivity in carbon nanotubes.