Normal state, superconductivity and quasiparticle Fermi surface of the strongly correlated oxide Sr2RuO4

The oxide superconductor Sr2RuO4 is emerging as an archetypal strongly correlated electron system. We review the experimental situation, focusing on Fermi surface specific probes. Quantum oscillation measurements have revealed a Fermi surface consisting of three slightly warped cylinders populated by quasiparticles with masses ranging from 3.4 to 14.6 times the bare electron mass. Then is strong evidence that Sr2RuO4 is a spin-triplet superconductor, and the simplicity of the Fermi surface combined with detailed knowlege of the quasiparticle properties from quantum oscillation and orbital specific NMR measurements means that Sr2RuO4 may be a key system for understanding unconventional superconductivity. We compare Sr2RuO4 With three-dimensional nearly ferromagnetic 3d-metals, and suggest that quasi-tno-dimensional spin-fluctuations may be responsible for the fact that Sr2RuO4 is the first nearly ferromagnetic metal to show superconductivity. (C) 1999 Elsevier Science B.V. All rights reserved.