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arXiv · 1107.2837

Approaching Zero-Temperature Metallic States in Mesoscopic Superconductor-Normal-Superconductor Arrays

Serena Eley·Sarang Gopalakrishnan·Paul M. Goldbart·Nadya Mason
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Abstract

Systems of superconducting islands placed on normal metal films offer tunable realizations of two-dimensional (2D) superconductivity; they can thus elucidate open questions regarding the nature of 2D superconductors and competing states. In particular, island systems have been predicted to exhibit zero-temperature metallic states. Although evidence exists for such metallic states in some 2D systems, their character is not well understood: the conventional theory of metals cannot explain them, and their properties are difficult to tune. Here, we characterize the superconducting transitions in mesoscopic island-array systems as a function of island thickness and spacing. We observe two transitions in the progression to superconductivity; both transition temperatures exhibit unexpectedly strong depression for widely spaced islands. These depressions are consistent with the system approaching zero-temperature metallic states. The nature of the transitions and the state between them is explained using a phenomenological model involving the stabilization of superconductivity on each island via a weak coupling to and feedback from its neighbors.

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Serena Eley, Sarang Gopalakrishnan, Paul M. Goldbart, Nadya Mason. 2011-07-14. Approaching Zero-Temperature Metallic States in Mesoscopic Superconductor-Normal-Superconductor Arrays. https://doi.org/10.1038/nphys2154

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