G. Baskaran, WHY IS SR2RUO4 NOT A HIGH T-C SUPERCONDUCTOR - ELECTRON CORRELATION, HUNDS COUPLING AND P-WAVE INSTABILITY, Physica. B, Condensed matter, 224(1-4), 1996, pp. 490-495
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.