Josephson current in s-wave superconductor / Sr_2RuO_4 junctions

Abstract

The Josephson current between an s-wave and a spin-triplet superconductor Sr${}_2$RuO${}_4$ (SRO) is studied theoretically. In spin-singlet / spin-triplet superconductor junctions, there is no Josephson current proportional to $\sin \varphi$ in the absence of the spin-flip scattering near junction interfaces, where $\varphi$ is a phase-difference across junctions. Thus a dominant term of the Josephson current is proportional to $\sin 2\varphi$ . The spin-orbit scattering at the interfaces gives rise to the Josephson current proportional to $\cos \varphi$, which is a direct consequence of the chiral paring symmetry in SRO.