Interaction-induced Renormalization of Andreev Reflection

TL;DR

This paper investigates how electron interactions affect Andreev reflection in one-dimensional systems, revealing significant phase renormalization and conductance suppression, which explains experimental observations in nanotube-superconductor junctions.

Contribution

It introduces a renormalization group framework that accounts for energy dependence in Andreev reflection, highlighting interaction effects on conductance.

Findings

Strong renormalization of Andreev reflection phase predicted.

Interaction suppresses Andreev conductance depending on normal resistance.

Explains experimental results in carbon nanotube-superconductor junctions.

Abstract

We analyze the charge transport between a one-dimensional weakly interacting electron gas and a superconductor within the scaling approach in the basis of scattering states. We derive the renormalization group equations, which fully account for the intrinsic energy dependence due to Andreev reflection. A strong renormalization of the corresponding reflection phase is predicted even for a perfectly transparent metal-superconductor interface. The interaction-induced suppression of the Andreev conductance is shown to be highly sensitive to the normal state resistance, providing a possible explanation of experiments with carbon-nanotube/superconductor junctions by Morpurgo et al. [Science 286, 263 (2001)].