Paraconductivity of pseudogapped superconductors

Abstract

We calculate Aslamazov-Larkin paraconductity ${\sigma }_{AL}(T)$ for a model of strongly disordered superconductors (dimensions $d=2,3$) with a large pseudogap whose magnitude strongly exceeds transition temperature $T_c$. We show that, within Gaussian approximation over Cooper-pair fluctuations, paraconductivity is just twice larger that the classical AL result at the same $\epsilon =(T-T_c)/T_c$. Upon decreasing $\epsilon$, Gaussian approximation is violated due to local fluctuations of pairing fields that become relevant at $\epsilon \le {\epsilon }_1\ll 1$. Characteristic scale ${\epsilon }_1$ is much larger than the width ${\epsilon }_2$ of the thermodynamical critical region, that is determined via the Ginzburg criterion, ${\epsilon }_2\approx {\epsilon }_1^d$. We argue that in the intermediate region ${\epsilon }_2\le \epsilon \le {\epsilon }_1$ 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 $\epsilon \le {\epsilon }_2$; in particular, conductivity occurs to be strongly inhomogeneous in real space.

16 pages, 10 figures

References in corpus (5)

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• Disorder-Induced Inhomogeneities of the Superconducting State Close to the Superconductor-Insulator Transition
• Eigenfunction fractality and pseudogap state near superconductor-insulator transition
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