SUPERCONDUCTIVITY FROM A NON-FERMI-LIQUID - A GINZBURG-LANDAU APPROACH

We present a microscopic derivation of the Ginzburg-Landau free-energy functional starting from a non-Fermi-liquid ground state characterize d by a single particle Green's function g(0)(k,omega) =omega(c)(-alpha )/(i omega-epsilon(k))(1-alpha). We assume a BCS-like pairing interact ion and obtain analytical expressions for the Ginzburg-Landau coeffici ents a (T) and b as functions of the scaling exponent alpha. We show h ow a nonvanishing value of the exponent alpha (which leads to a breakd own of Fermi-liquid theory in the normal state) yields qualitatively a nd quantitatively different results in the superconducting state.