WHY IS SR2RUO4 NOT A HIGH T-C SUPERCONDUCTOR - ELECTRON CORRELATION, HUNDS COUPLING AND P-WAVE INSTABILITY

Sr2RuO4 is a layered superconductor with a T-c approximate to 0.95 K. The electrical resistivity is strongly anisotropic and has an unusual T dependence: rho(ab) similar to T-2 for T < 100 K and rho(ab) similar to T for T > 100 K; the ratio rho(c)/rho(ab) is about 850 around 4 K and 220 around 290 K. dHvA and SdH experiments show the presence of th ree anisotropic 'Fermi surfaces'. Experiments on Sr2RuO4 and related o xides indicate that this conductor is close to a spin 1 Mott insulatin g state. We present a model for the insulating and conducting stales o f these compounds and a mechanism for the metal-insulator transition. We argue that there are two bands of non-Fermi liquids which are close to half filling and an almost full band. The residual Hund's coupling in this (primarily 4d) band is argued to cause triplet correlations a mong the low-energy spinon excitations of the two bands of non-Fermi l iquids below about 100 K. Based on this, we suggest that the experimen tally observed superconducting state is likely to be a triplet p-wave type. Some other predictions are also made.