Conductance properties of nanotubes coupled to superconducting leads: signatures of Andreev states dynamics

TL;DR

This paper investigates the conductance behavior of carbon nanotubes with superconducting contacts, revealing how Andreev states influence zero bias peaks and their dynamics under bias voltage.

Contribution

It combines experimental and theoretical approaches to analyze Andreev state dynamics and their impact on conductance in nanotube-superconductor systems.

Findings

Zero bias conductance peaks can exceed the normal limit.

The linear conductance regime depends on relaxation rates.

Theoretical models fit experimental data well.

Abstract

We present a combined experimental and theoretical analysis of the low bias conductance properties of carbon nanotubes coupled to superconducting leads. In the Kondo regime the conductance exhibits a zero bias peak which can be several times larger than the unitary limit in the normal case. This zero bias peak can be understood by analyzing the dynamics of the subgap Andreev states under an applied bias voltage. It is shown that the existence of a linear regime is linked to the presence of a finite relaxation rate within the system. The theory provides a good fitting of the experimental results.