Anomalous mesoscopic kinetics in disordered superconductors

Abstract

We study anomalous mesoscopic transport effects at the onset of the\nsuperconducting transition focusing on the observed large Nernst-Ettinghausen\nsignal in disordered thin films. In the vicinity of the transition, as the\nGinzburg-Landau coherence length of preformed Cooper pairs diverges,\nshort-range mesoscopic fluctuations are equivalent to local fluctuations of the\ncritical temperature. As a result, the dynamical susceptibility function of\npair propagation acquires a singular mesoscopic component, and consequently,\nsuperconducting correlations give rise to enhanced mesoscopic fluctuations of\nthermodynamic and transport characteristics. In contrast to disordered normal\nmetals, the root-mean-square value of mesoscopic conductivity fluctuations\nceases to be universal and displays strong dependence on dimensionality,\ntemperature, and under certain conditions can exceed its quantum normal state\nvalue by a large factor. Interestingly, we find different universality as\nmagnetic susceptibility, conductivity, and transverse magnetic thermopower\ncoefficients all display the same temperature dependence. Finally, we discuss\nan enhancement of mesoscopic effects in the Seebeck thermoelectricity and Hall\nconductivity fluctuations as mediated by emergent superconductivity.\n