PERTURBATIVE STUDIES OF THE CONDUCTIVITY IN THE VORTEX-LIQUID REGIME

We calculate the Aslamazov-Larkin term of the conductivity in the pres ence of a magnetic field applied along the c axis from the time-depend ent Ginzburg-Landau equation perturbatively using two approaches. In t he first a uniform electric field is explicitly applied; in the second the Kubo formula is used to extract the linear;response. The former y ields a version of the flux-flow formula for the uniform ab-plane cond uctivity, sigma(xx)(k=0), that holds to all orders of perturbation the ory. Obtaining the same result from the Kubo formula requires consider able cancellation of terms. We also use the Kubo calculation to examin e the nonlocal ab-plane conductivity, sigma(xx)(k not equal 0) (where the cancellations no longer occur), as well as the nonlocal c-axis con ductivity sigma(zz)(k not equal 0), and look for the perturbative prec ursors of the growing viscous length scales. In addition, we consider the effects of weak disorder-both uncorrelated (point defects) and cor related (columnar and planar defects).