Single-walled carbon nanotube weak links: from Fabry-P\'{e}rot to Kondo regime

TL;DR

This paper explores supercurrents in single-walled carbon nanotubes, comparing Kondo and Fabry-Pérot regimes, revealing distinct behaviors and evidence of Andreev level renormalization.

Contribution

It provides the first detailed comparison of supercurrents in the Kondo and Fabry-Pérot regimes within the same nanotube system.

Findings

Wide range of Kondo temperatures (1-14 K) observed.

Critical current shows two distinct branches related to Kondo conductance splitting.

Evidence of renormalized Andreev levels in the Kondo regime.

Abstract

We have investigated proximity-induced supercurrents in single-walled carbon nanotubes in the Kondo regime and compared them with supercurrents obtained on the same tube with Fabry-P\'{e}rot resonances. Our data display a wide distribution of Kondo temperatures \emph{$T_K$} = 1 - 14 K, and the measured critical current $I_{CM}$ vs. \emph{$T_K$} displays two distinct branches; these branches, distinguished by zero-bias splitting of the normal-state Kondo conductance peak, differ by an order of magnitude at large values of $T_K$. Evidence for renormalization of Andreev levels in Kondo regime is also found.