Interplay of ferromagnetism and triplet superconductivity in a Josephson junction

TL;DR

This paper investigates the complex interplay between ferromagnetism and triplet superconductivity in Josephson junctions, revealing new effects such as current flow at zero phase difference and non-analytic critical currents influenced by barrier properties.

Contribution

The study extends previous models by including potential scattering and arbitrary ferromagnetic orientations, uncovering novel phenomena and robustness of certain Josephson current switching behaviors.

Findings

Josephson current can flow at zero phase difference.

Critical current exhibits strong non-analyticities.

Temperature dependence of current is highly sensitive to barrier terms.

Abstract

In this paper we extend our earlier analysis of the novel Josephson effect in triplet superconductor--ferromagnet--triplet superconductor (TFT) junctions [B. Kastening \emph{et al.}, Phys. Rev. Lett. {\bf{96}}, 047009 (2006)]. In our more general formulation of the TFT junction we allow for potential scattering at the barrier and an arbitrary orientation of the ferromagnetic moment. Several new effects are found upon the inclusion of these extra terms: for example, we find that a Josephson current can flow even when there is vanishing phase difference between the superconducting condensates on either side of the barrier. The critical current for a barrier with magnetization parallel to the interface is calculated as a function of the junction parameters, and is found to display strong non-analyticities. Furthermore, the Josephson current switches first identified in our previous work are found to be robust features of the junction, while the unconventional temperature-dependence of the current is very sensitive to the extra terms in the barrier Hamiltonian.