Impurity scattering in metallic carbon nanotubes with superconducting pair potentials

TL;DR

This paper theoretically investigates how superconducting pair potentials influence impurity scattering in metallic carbon nanotubes, revealing that nonmagnetic impurities do not impede supercurrents due to cancellation effects.

Contribution

It demonstrates that superconducting correlations suppress backward scattering of quasiparticles, explaining why impurities do not hinder supercurrents in proximity-induced superconducting nanotubes.

Findings

Backward scattering vanishes in the normal state.

Superconducting pair correlations eliminate backward scattering of quasiparticles.

Impurities do not hinder supercurrent due to cancellation of electron-hole scattering effects.

Abstract

Effects of the superconducting pair potential on the impurity scattering processes in metallic carbon nanotubes are studied theoretically. The backward scattering of electrons vanishes in the normal state. In the presence of the superconducting pair correlations, the backward scatterings of electron- and hole-like quasiparticles vanish, too. The impurity gives rise to backward scatterings of holes for incident electrons, and it also induces backward scatterings of electrons for incident holes. Negative and positive currents induced by such the scatterings between electrons and holes cancel each other. Therefore, the nonmagnetic impurity does not hinder the supercurrent in the regions where the superconducting proximity effects occur. Relations with experiments are discussed.