Paraconductivity of pseudogapped superconductors

Igor Poboiko


We calculate Aslamazov-Larkin  paraconductity σAL(T)  for a model of  strongly disordered superconductors (dimensions d=2,3) with a  large pseudogap whose magnitude strongly  exceeds transition temperature Tc.  We show that, within Gaussian approximation over Cooper-pair fluctuations, paraconductivity is just twice larger that the classical AL result at the same  ε = (T-Tc)/Tc.  Upon decreasing ε,  Gaussian approximation is violated due to local fluctuations of pairing fields that become relevant at ε < ε1 << 1.  Characteristic scale ε1 is  much larger than the width ε2 of the thermodynamical critical region, that is determined via  the Ginzburg criterion, ε2 ≃ ε1d. We argue that in the intermediate region ε2 < ε < ε1 paraconductivity follows the same AL power law, albeit with another (yet unknown) numerical prefactor. At further decrease of the temperature, all kinds of fluctuational corrections become strong at  ε < ε2; in particular, conductivity occurs to be  strongly  inhomogeneous in real space.