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 $T_{\mathrm{c}}=1.5\mathrm{}\mathrm{K}$ 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 $T_{\mathrm{c}}$.