Evidence for the Sr2RuO4 intercalations in the Sr3Ru2O7 region of the Sr3Ru2O7-Sr2RuO4 eutectic system

TL;DR

This study provides evidence that Sr2RuO4 intercalations within Sr3Ru2O7 regions induce superconductivity, supported by resistivity measurements showing anisotropic superconducting behavior consistent with thin slab embedding.

Contribution

It offers experimental support for the presence of Sr2RuO4 thin slabs in Sr3Ru2O7 regions, explaining the observed superconducting transitions in eutectic crystals.

Findings

Superconductivity observed only in ab-plane resistivity

Pure Sr3Ru2O7 does not superconduct down to 15 mK

Resistivity data supports Sr2RuO4 slab scenario

Abstract

Although Sr3Ru2O7 has not been reported to exhibit superconductivity so far, ac susceptibility measurements revealed multiple superconducting transitions occurring in the Sr3Ru2O7 region cut from Sr3Ru2O7-Sr2RuO4 eutectic crystals. Based on various experimental results, some of us proposed the scenario in which Sr2RuO4 thin slabs with a few layers of the RuO2 plane are embedded in the Sr3Ru2O7 region as stacking faults and multiple superconducting transitions arise from the distribution of the slab thickness. To examine this scenario, we measured the resistivity along the ab plane (rho_ab) using a Sr3Ru2O7-region sample cut from the eutectic crystal, as well as along the c axis (rho_c) using the same crystal. As a result, we detected resistance drops associated with superconductivity only in rho_ab, but not in rho_c. These results support the Sr2RuO4 thin-slab scenario. In addition, we measured the resistivity of a single crystal of pure Sr3Ru2O7 with very high quality and found that pure Sr3Ru2O7 does not exhibit superconductivity down to 15 mK.