Superconducting spintronic tunnel diode

TL;DR

This paper introduces a superconducting spintronic tunnel diode that leverages EuS thin films to achieve significant rectification at cryogenic temperatures, promising advancements in sensitive radiation detection and low-dissipation superconducting electronics.

Contribution

The work demonstrates a novel superconducting spintronic diode using EuS and Al layers, achieving high rectification and modeling its behavior, which is a new approach in superconducting spintronics.

Findings

Achieved up to 40% rectification at small voltages (~200 μV).

Linked rectification to spin polarization via theoretical modeling.

Potential applications in highly-sensitive radiation detection and superconducting electronics.

Abstract

Diodes are key elements for electronics, optics, and detection. The search for a material combination providing the best performances for the required application is continuously ongoing. Here, we present a superconducting spintronic tunnel diode based on the strong spin filtering and splitting generated by an EuS thin film between a superconducting Al and a normal metal Cu layer. The Cu/EuS/Al tunnel junction achieves a large rectification (up to $\sim40$\%) already for a small voltage bias ($\sim 200$ $\mu$V) thanks to the small energy scale of the system: the Al superconducting gap. With the help of an analytical theoretical model we can link the maximum rectification to the spin polarization of the barrier and describe the quasi-ideal Schottky-diode behavior of the junction. This cryogenic spintronic rectifier is promising for the application in highly-sensitive radiation detection for which two different configurations are evaluated. In addition, the superconducting diode may pave the way for future low-dissipation and fast superconducting electronics.