Superconductivity in a layered perovskite without copper

FOLLOWING the discovery of superconductivity at ~30 K in La_2-xBa_xCuO₄ (ref. 1), a large number of related compounds have been found that are superconducting at relatively high temperatures. The feature common to all of these materials is a layered crystal structure based on a perovskite template and containing planar networks of copper and oxygen. This raises the question of whether superconductivity can occur in layered perovskites that do not contain copper. To the best of our knowledge, no such material has been found to date, despite nearly a decade of searching. We describe here the discovery of superconductivity in Sr₂RuO₄, a layered perovskite isostructural with La_2-xBa_xCuO₄ (Fig. 1). Our results demonstrate that the presence of copper is not a prerequisite for the existence of superconductivity in a layered perovskite. But the low value of the superconducting transition temperature (T_c = 0.93 K) points towards a special role for copper in the high-temperature superconductors.