Superconductivity in BaBi₃ formed by in situ reduction at a Metal/Oxide heterointerface

Oxygen-scavenging at oxide heterointerfaces has recently emerged as an effective route to stabilize metastable phases exhibiting novel phenomena such as high mobility two-dimensional electron gases and high-temperature superconductivity. We report the formation of the BaBi₃ phase during the growth of metal (Eu, Al)/oxide (BaBiO₃) heterostructures, where in-situ interfacial reduction of BaBiO₃ leads to the formation of BaBi₃ and BaO_x. X-ray diffraction confirms the coexistence of BaBi₃ and BaO_x phases, verifying the reduction process. Electrical transport measurements reveal superconductivity with an onset temperature around 6K, comparable to bulk BaBi₃. Angle-dependent magnetotransport and current-voltage characteristics indicate a quasi-two-dimensional superconducting state. These results demonstrate a viable pathway for stabilizing metastable superconducting phases through control interfacial redox reactions in metal/oxide systems.