Enhancement of Superconductivity ofSr2RuO4to 3 K by Embedded Metallic Microdomains

We have found that the quasi-two-dimensional superconductor $\mathrm{Sr}{}_{2}\mathrm{RuO}{}_{4}$ with the intrinsic transition temperature ${T}_{\mathrm{c}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.5\mathrm{K}$ exhibits a remarkable enhancement in ${T}_{\mathrm{c}}$ up to 3 K, if lamellar microdomains of ruthenium metal are embedded. Measurements of the anisotropy in the upper critical fields indicate that the 3-K superconductivity is sustained essentially in the layered structure of $\mathrm{Sr}{}_{2}\mathrm{RuO}{}_{4}$. We suggest that the enhanced interlayer coherence provided via metallic Ru plays a key role in the doubling of ${T}_{\mathrm{c}}$.