Single-walled carbon nanotube weak links in Kondo regime with zero-field splitting

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-Pérot resonances. Our data display a wide distribution of Kondo temperatures TK=1–14 K, and the measured critical current ICM vs TK displays two distinct branches; these branches, distinguished by zero-field splitting of the normal-state Kondo conductance peak, differ by an order of magnitude at large values of TK. Evidence for renormalization of Andreev levels in Kondo regime is also found.