Spin-split superconductivity in spin-orbit coupled hybrid nanowires with ferromagnetic barriers

TL;DR

This study investigates spin-split superconductivity in InAs nanowires with ferromagnetic insulators and superconducting shells, revealing unique transport phenomena and establishing a platform for spin-triplet pairing exploration.

Contribution

It demonstrates proximity-induced superconductivity through a ferromagnetic insulator in hybrid nanowires, highlighting the role of spin-orbit coupling in spin-split superconducting states.

Findings

Observation of a hysteretic superconducting window with supercurrent near coercive field

Identification of a three-peak superconducting gap in tunneling spectra

Theoretical model showing spin mixing driven by spin-orbit coupling is crucial

Abstract

We report transport studies of hybrid Josephson junctions based on semiconducting InAs nanowires with fully overlapping epitaxial ferromagnetic insulator EuS and superconducting Al partial shells. Current-biased measurements reveal a hysteretic superconducting window with a sizable supercurrent near the coercive field of the ferromagnetic insulator, accompanied by multiple Andreev reflections. Tunneling spectroscopy shows a superconducting gap characterized by three peaks, which we attribute to tunneling between exchange-split superconductors. A theoretical model reproduces the observed features and indicates that spin mixing, driven by sizable spin-orbit coupling, is essential to their formation. Our results demonstrate proximity-induced superconductivity through a ferromagnetic insulator and establish a new platform for exploring spin-triplet pairing.