Single crystals of the Sr2RuO4-Ru eutectic system are known to exhibit enhanced superconductivity at 3~K, in addition to the bulk superconductivity of Sr2RuO4 at 1.5~K. The 1.5-K phase is believed to be a spin-triplet, chiral p-wave state with the multi-component order parameter, giving rise to chiral domain structure. In contrast, the 3-K phase is attributable to enhanced superconductivity of Sr2RuO4 in the strained interface region between Ru inclusion of a few to tens of micrometers in size and the surrounding Sr2RuO4. We investigate the dynamic behavior of a topological junction, where a superconductor is surrounded by another superconductor. Specifically, we fabricated Nb/Ru/Sr2RuO4 topological superconducting junctions, in which the difference in phase winding between the s-wave superconductivity in Ru micro-islands induced from Nb and the superconductivity of Sr2RuO4 mainly governs the junction behavior. Comparative results of the asymmetry, hysteresis and noise in junctions with different sizes, shapes, and configurations of Ru inclusions are explained by the chiral domain-wall motion in these topological junctions. Furthermore, a striking difference between the 1.5-K and 3-K phases is clearly revealed: the large noise in the 1.5-K phase sharply disappears in the 3-K phase. These results confirm the multi-component order-parameter superconductivity of the bulk Sr2RuO4, consistent with the chiral p-wave state, and the proposed non-chiral single-component superconductivity of the 3-K phase.
@article{arxiv.1703.01814,
title = {Multi-component order parameter superconductivity of Sr$_2$RuO$_4$ revealed by topological junctions},
author = {M. S. Anwar and R. Ishiguro and T. Nakamura and M. Yakabe and S. Yonezawa and H. Takayanagi and Y. Maeno},
journal= {arXiv preprint arXiv:1703.01814},
year = {2017}
}