The Unconventional Superconductivity of Sr2RuO4

The authors review the evidence for unconventional superconductivity in Sr{sub 2}RuO{sub 4}; the pairing in this material is certainly non-s-wave, and most of the current observations can be accounted for by a particular p-wave state, which is doubly degenerate and breaks time-reversal symmetry. The observations of the flux lattice by small-angle neutron scattering contribute to this picture. The square flux lattice and the intensity of the diffracted signal indicate that superconductivity resides primarily on the {gamma} sheet of the Fermi surface, which is derived from the Ru--d{sub xy} orbitals. This is in agreement with the orbital-dependent p-wave scenario. Furthermore, the shape of the flux lines derived from these measurements is strongly indicative of a two-component order parameter.