Universal conductance correction in a tunable strongly coupled nanogranular metal |
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Authors: | Sachser Roland Porrati Fabrizio Schwalb Christian H Huth Michael |
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Institution: | Physikalisches Institut, Goethe-Universit?t, Frankfurt am Main, Germany. sachser@physik.uni-frankfurt.de |
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Abstract: | We present temperature-dependent conductivity data obtained on a sample set of nanogranular Pt-C with finely tuned intergrain tunnel coupling strength g. For samples in the strong-coupling regime g > g(C), characterized by a finite conductivity for T→0, we find a logarithmic behavior at elevated temperatures and a crossover to a √T behavior at low temperatures over a wide range of coupling strengths g(C) ≈ 0.25 < g ≤ 3. The experimental observation for g > 1 is in very good agreement with recent theoretical findings on ordered granular metals in three spatial dimensions. The results indicate a validity of the predicted universal conductivity behavior that goes beyond the immediate range of the approach used in the theoretical derivation. |
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