Andreev Current-Induced Dissipation in a Hybrid Superconducting Tunnel Junction

TL;DR

This paper investigates how Andreev current causes dissipation in hybrid superconducting tunnel junctions, impacting cooling efficiency by introducing Joule heating that dominates over quasiparticle cooling in certain conditions.

Contribution

It provides a quantitative analysis of Andreev current-induced dissipation and its effect on electronic temperature evolution in superconducting micro-coolers.

Findings

Andreev current causes significant Joule heating in the normal metal.

Dissipation from Andreev current can surpass quasiparticle cooling effects.

The heat balance analysis explains the temperature evolution under subgap bias.

Abstract

We have studied hybrid superconducting micro-coolers made of a double Superconductor-Insulator-Normal metal tunnel junction. Under subgap conditions, the Andreev current is found to dominate the single-particle tunnel current. We show that the Andreev current introduces additional dissipation in the normal metal equivalent to Joule heating. By analyzing quantitatively the heat balance in the system, we provide a full description of the evolution of the electronic temperature with the voltage. The dissipation induced by the Andreev current is found to dominate the quasiparticle tunneling-based cooling over a large bias range.