Josephson effect due to the long-range odd-frequency triplet superconductivity in SFS junctions with Neel domain walls

TL;DR

This paper investigates how long-range odd-frequency triplet superconducting correlations in a multidomain ferromagnet influence the Josephson effect in SFS junctions, revealing a $ ext{pi}$-state and modifications to the density of states.

Contribution

It demonstrates the emergence of long-range triplet correlations in Neel domain walls and their impact on Josephson current and density of states in SFS junctions.

Findings

Long-range triplet component spreads over a distance $\xi_T$.

The junction is in the $ ext{ extpi}$ state when F layer is thin.

Density of states is affected by the triplet component.

Abstract

We consider a SFS Josephson junction made of two superconductors S and a multidomain ferromagnet F with an in-plane magnetization. We assume that the neighboring domains of the ferromagnet are separated by Neel domain walls. An odd-frequency triplet long-range component of superconducting correlations arises in the domain walls and spreads into the domains over a long distance of the order $\xi_T = \sqrt{D / 2 \pi T}$, where $D$ is the diffusion coefficient (dirty limit is implied). We calculate the contribution of this component to the Josephson current in the situation when conventional short-range components exponentially decay over the thickness of the F layer and can be neglected. In the limit when the thickness of the F layer is much smaller than the penetration length of the long-range component, we find that the junction is in the $\pi$ state. We also analyze a correction to the density of states due to the long-range triplet component.