Direct penetration of spin-triplet superconductivity into a ferromagnet in Au/SrRuO3/Sr2RuO4 junctions

TL;DR

This paper demonstrates the first ferromagnet/spin-triplet superconductor device showing superconductivity penetration into a ferromagnet over 15 nm, enabling potential advances in superconducting spintronics without complex magnetic interfaces.

Contribution

It reports the experimental realization of spin-triplet superconductivity induction into a ferromagnet using a SrRuO3/Sr2RuO4 hybrid, showing direct penetration without interfacial magnetic complexity.

Findings

Superconductivity penetrates 15 nm into SrRuO3 from Sr2RuO4.

Andreev-reflection features indicate spin-triplet proximity effect.

First demonstration of FM/TSC device with triplet superconductivity penetration.

Abstract

Efforts have been ongoing to establish superconducting spintronics utilizing ferromagnet/superconductor heterostructures1. Previously reported devices are based on spin-singlet superconductors (SSCs), where the spin degree of freedom is lost. Spin-polarized supercurrent induction in ferromagnetic metals (FMs) is achieved even with SSCs, but only with the aid of interfacial complex magnetic structures, which severely affect information imprinted to the electron spin. Use of spin-triplet superconductors (TSCs) with active spins potentially overcomes this difficulty and further leads to novel functionalities. Here, we report spin-triplet superconductivity induction into a FM SrRuO3 from a leading TSC candidate Sr2RuO4, by fabricating microscopic devices using an epitaxial SrRuO3/Sr2RuO4 hybrid. The differential conductance, exhibiting Andreev-reflection features with multiple energy scales up to around half tesla, indicates the penetration of superconductivity over a considerable distance of 15 nm across the SrRuO3 layer without help of interfacial complex magnetism. This demonstrates the first FM/TSC device exhibiting the spin-triplet proximity effect.