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Superconductivity in a Mesoscopic Double Square Loop: Effect of Imperfections

V. M. Fomin·J. T. Devreese·V. Bruyndoncx·V. V. Moshchalkov
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Abstract

We have generalized the network approach to include the effects of short-range imperfections in order to analyze recent experiments on mesoscopic superconducting double loops. The presence of weakly scattering imperfections causes gaps in the phase boundary $B(T)$ or $Φ(T)$ for certain intervals of $T$, which depend on the magnetic flux penetrating each loop. This is accompanied by a critical temperature $T_c(Φ)$, showing a smooth transition between symmetric and antisymmetric states. When the scattering strength of imperfections increases beyond a certain limit, gaps in the phase boundary $T_c(B)$ or $T_c(Φ)$ appear for values of magnetic flux lying in intervals around half-integer $Φ_0=hc/2e$. The critical temperature corresponding to these values of magnetic flux is determined mainly by imperfections in the central branch. The calculated phase boundary is in good agreement with experiment.

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V. M. Fomin, J. T. Devreese, V. Bruyndoncx, V. V. Moshchalkov. 2000-01-14. Superconductivity in a Mesoscopic Double Square Loop: Effect of Imperfections. https://doi.org/10.1103/physrevb.62.9186

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