Efficient Peltier refrigeration by a pair of normal metal/ insulator/superconductor junctions

TL;DR

This paper demonstrates that a symmetric SINIS structure with normal metal/insulator/superconductor junctions can efficiently cool from 300 mK to about 100 mK, showing potential for low-temperature refrigeration.

Contribution

The paper introduces and experimentally verifies a novel SINIS-based Peltier refrigerator capable of significant cooling at sub-Kelvin temperatures.

Findings

Achieved cooling from 300 mK to 100 mK

Estimated cooling power of 1.5 pW at 300 mK

Demonstrated effective operation of symmetric SINIS structure

Abstract

We suggest and demonstrate in experiment that two normal metal /insulator/ superconductor (NIS) tunnel junctions combined in series to form a symmetric SINIS structure can operate as an efficient Peltier refrigerator. Specifically, it is shown that the SINIS structure with normal-state junction resistances 1.0 and 1.1 k$\Omega$ is capable of reaching a temperature of about 100 mK starting from 300 mK. We estimate the corresponding cooling power to be 1.5 pW per total junction area of 0.8 $\mu$m$^2$ at $T= 300$ mK.