Effects of fluctuations and Coulomb interaction on the transition temperature of granular superconductors

Abstract

We investigate the suppression of superconducting transition temperature in granular metallic systems due to (i) fluctuations of the order parameter (bosonic mechanism) and (ii) Coulomb repulsion (fermionic mechanism) assuming large tunneling conductance between the grains $g_T\gg 1$. We find the correction to the superconducting transition temperature for 3$d$ granular samples and films. We demonstrate that if the critical temperature $T_c>g_T\delta$, where $\delta$ is the mean level spacing in a single grain the bosonic mechanism is the dominant mechanism of the superconductivity suppression, while for critical temperatures $T_c<g_T\delta$ the suppression of superconductivity is due to the fermionic mechanism.

arXiv comment12 pages, 9 figures, several sections clarifying the details of our calculations are added

References in corpus (8)

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• Transition from insulating to a non-insulating temperature dependence of the conductivity in granular metals
• Quantum interference and Coulomb interaction in arrays of tunnel junctions
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Cited by in corpus (8)

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• Two-Fluid Model for Granular Superconductors
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• Superfluid stiffness renormalization and critical temperature enhancement in a composite superconductor
• Superconducting Fluctuation Corrections to the Thermal Current in Granular Metals
• Scale-dependent theory of the disordered electron liquid
• Effects of critical fluctuations and dimensionality on the jump in specific heat at the superconducting transition temperature: Application to YBa2Cu_3 O_7 - δ, Bi_2 Sr_2CaCu_2 O_8+δand KOs_2 O_6 compounds
• Enhanced superconducting-fluctuation effects on thermodynamic properties in BCS-BEC-crossover regime