Critical current of the Sr2 RuO4 - Sr3 Ru2 O7 eutectic system

We report critical current measurements of the Sr2 RuO4 - Sr3 Ru2 O7 eutectic system, a solid mixture of the spin-triplet superconductor Sr2 RuO4 and the nearly ferromagnetic metal Sr3 Ru2 O7. Our results reveal that this eutectic forms an unusual superconducting state with features distinct from those of the pure Sr2 RuO4 phase. We observe a crossover from Ambegaokar-Baratoff to Ginzburg-Landau type behavior in the temperature dependence of the critical current, similar to the behavior of Josephson weak-link networks in granular high- Tc cuprates. Our results suggest that large regions of Sr3 Ru2 O7 in this solid mixture may become superconducting by an unusual proximity effect.