Superconductivity in ultra-thin carbon nanotubes and carbyne-nanotube composites: an ab-initio approach

TL;DR

This paper presents an ab-initio computational approach to predict superconducting transition temperatures in ultra-thin carbon nanotubes and composites, revealing potential Tc up to 60K and methods to enhance superconductivity.

Contribution

The study introduces a novel computational algorithm for predicting superconductivity in ultrathin SWCNTs, accounting for geometry, pressure, and chirality effects, and explores enhancement in carbon nanotube composites.

Findings

Maximum Tc of 60K predicted for optimized nanotubes.

Embedding a carbon chain in (5,0) SWCNTs increases Tc by 2.2 times.

Curvature and composite effects significantly influence superconductivity.

Abstract

The superconductivity of the 4-angstrom single-walled carbon nanotubes (SWCNTs) was discovered more than a decade ago, and marked the breakthrough of finding superconductivity in pure elemental undoped carbon compounds. The van Hove singularities in the electronic density of states at the Fermi level in combination with a large Debye temperature of the SWCNTs are expected to cause an impressively large superconducting gap. We have developed an innovative computational algorithm specially tailored for the investigation of superconductivity in ultrathin SWCNTs. We predict the superconducting transition temperature of various thin carbon nanotubes resulting from electron-phonon coupling by an ab-initio method, taking into account the effect of radial pressure, symmetry, chirality (N,M) and bond lengths. By optimizing the geometry of the carbon nanotubes, a maximum Tc of 60K is found. We also use our method to calculate the Tc of a linear carbon chain embedded in the center of (5,0) SWCNTs. The strong curvature in the (5,0) carbon nanotubes in the presence of the inner carbon chain provides an alternative path to increase the Tc of this carbon composite by a factor of 2.2 with respect to the empty (5,0) SWCNTs.