Spin fluctuation and unconventional pairing in Sr2RuO4

Sr2RuO4 with T-c=0.7 K with the same layered perovskite structure as La2CuO4 is the exchange-enhanced Pauli paramagnet with the two dimensional (2D) electronic structure. The superconductivity of has been found to be unconventional from the nuclear relaxation behavior exhibiting a sharp decrease with no coherence peak just below T-c and the T1T=constant behavior well below Tc. In comparison with the high-T-c Bi2Sr2CaCu2O8+y (Bi2212) and the 3D analogue of exchange-enhanced Pauli paramagnet CeCo2, the similarity and dissimilarity are presented on the normal and superconducting states.