High-Temperature Superconducting Oxide Without Copper at Ambient Pressure

The discovery of superconductivity in the Ba-La-Cu-O system (the cuprate) at 30 K range in 1986 marked a significant breakthrough, as it far exceeded the highest known critical temperature (T_c) at the time and surpassed the predicted 30 K limit, which was thought to be the maximum before phonon-mediated electron pairing would break down due to thermal excitation. Despite recent successful observations of superconductivity in nickel-oxide-based compounds (the nickelate), achieving superconductivity above 30 K at ambient pressure in a system that is isostructural to the cuprates but without copper has remained elusive. Here, we report superconductivity with a Tc above 35 K under ambient pressure in hole-doped, late rare-earth infinite-layer nickel oxide (Sm-Eu-Ca-Sr)NiO₂ thin films. Electron microscopy indicates a small thickness of approximately 2 nanometers of the infinite-layer phase stabilized in the present samples, suggesting that higher temperature superconductivity should be observable in cleaner bulk crystals. Our result demonstrates the potential of achieving high-temperature superconductivity using other 3d metal oxides beyond copper oxides as the building blocks for superconductivity, offering a promising platform for further exploration and understanding of high-temperature superconductivity.