Odd-parity superconductivity in Sr2RuO4

Phase-sensitive measurements were made on Sr2RuO4 to establish unambiguously the odd-parity pairing in this material. The critical current of Au0.5In0.5-Sr2RuO4 superconducting quantum interference devices prepared on Sr2RuO4 single crystals was found to be a maximum for devices with junctions on the same side of the crystal and a minimum for devices with junctions on opposite sides, in the limit of zero magnetic flux; these findings indicate that the phase of the superconducting order parameter in Sr2RuO4 changes by it under inversion. This result verifies the odd-parity pairing symmetry and the formation of spin-triplet Cooper pairs in Sr2RuO4.