Ultra-efficient Cooling in Ferromagnet-Superconductor Microrefrigerators

TL;DR

This paper proposes a ferromagnet-superconductor contact scheme for electron microrefrigeration, achieving high cooling power densities and significant electronic temperature reductions, with CrO₂/Al bilayers as promising candidates.

Contribution

It introduces a novel ferromagnet-superconductor microrefrigeration scheme with high efficiency and identifies specific material candidates for implementation.

Findings

Cooling power densities up to 600 nW/μm² achieved

Electronic temperature reductions exceed existing superconductor-normal metal contacts

CrO₂/Al bilayers are ideal for device implementation

Abstract

A promising scheme for electron microrefrigeration based on ferromagnet-superconductor contacts is presented. In this setup, cooling power densities up to 600 nW/$\mu$m$^2$ can be achieved leading to electronic temperature reductions largely exceeding those obtained with existing superconductor-normal metal tunnel contacts. Half-metallic CrO$_2$/Al bilayers are indicated as ideal candidates for the implementation of the device.