Giant Triplet Proximity Effect in $\pi$-biased Josephson Junctions with Spin-Orbit Coupling

TL;DR

This paper demonstrates that intrinsic spin-orbit coupling in diffusive Josephson junctions induces a giant proximity effect at phase difference π, enabling control and detection of spin-triplet superconductivity through symmetry-based analysis.

Contribution

It reveals a novel giant triplet proximity effect at π phase difference caused by spin-orbit coupling, supported by symmetry arguments and numerical analysis.

Findings

Giant triplet proximity effect occurs at φ=π with spin-orbit coupling.

Spectroscopic signature of triplets is observable throughout the ferromagnetic layer.

Effect is independent of specific experimental parameters, based on symmetry considerations.

Abstract

In diffusive Josephson junctions the phase-difference $\phi$ between the superconductors strongly influences the spectroscopic features of the layer separating them. The observation of a uniform minigap and its phase modulation were only recently experimentally reported, demonstrating agreement with theoretical predictions up to now - a vanishing minigap at $\phi=\pi$. Remarkably, we find that in the presence of intrinsic spin-orbit coupling a giant proximity effect due to spin-triplet Cooper pairs can develop at $\phi=\pi$, in complete contrast to the suppressed proximity effect without spin-orbit coupling. We here report a combined numerical and analytical study of this effect, proving its presence solely based on symmetry arguments, which makes it independent of the specific parameters used in experiments. We show that the spectroscopic signature of the triplets is present throughout the entire ferromagnetic layer. Our finding offers a new way to artificially create, control and isolate spin-triplet superconductivity.