Mechanism of spin-triplet superconductivity in Sr2RuO4

The unique Fermi surfaces and their nesting properties of Sr2RuO4 are consi dered. The existence of unconventional superconductivity is demonstrated fo r the first time, by magnetic interactions (due to nesting) and phonon-medi ated interactions. Two possible mechanisms of spin-triplet superconductivit y are pointed out: one is due to the quasi-1D nature of the alpha and beta sheets of the Fermi surface and other is due to the anisotropy of antiferro magnetic (AF) fluctuations. The odd-parity superconductivity is favored in the alpha and beta sheets of the Fermi surface, and various superconductivi ties are possible in the gamma sheet. There area number of possible odd-par ity gaps, which include the gaps with nodes, the breaking of time-reversal symmetry and d parallel to(z) over cap.