Paraconductivity of granular Al films at high reduced temperatures and magnetic fields

The electrical conductivity induced near the superconducting transition by thermal fluctuations was measured in different granular aluminum films. The seemingly anomalous behavior at high reduced temperatures and magnetic fields is explained by taking into account a total-energy cutoff in the superc...

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Bibliographic Details
Published in:Physical review. B 2019-09, Vol.100 (10), Article 104509
Main Authors: Sóñora, D., Carballeira, C., Ponte, J. J., Vidal, F., Grenet, T., Mosqueira, J.
Format: Article
Language:English
Subjects:
Aluminum
Coherence length
Condensed Matter
Disordered Systems and Neural Networks
Electrical resistivity
Magnetic fields
Physics
Superconductivity
Variations
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Summary:The electrical conductivity induced near the superconducting transition by thermal fluctuations was measured in different granular aluminum films. The seemingly anomalous behavior at high reduced temperatures and magnetic fields is explained by taking into account a total-energy cutoff in the superconducting fluctuation spectrum in both the direct (Aslamazov-Larkin) and the indirect (anomalous Maki-Thompson) contributions to the fluctuation effects. The analysis allowed a reliable determination of the coherence length amplitudes, which resulted to be much larger (20–48 nm) than the grains size (5–10 nm). This suggests that the grains are strongly Josephson-coupled, while the Tc value is still as high as twice the bulk value. These results could contribute to identifying the mechanisms enhancing Tc in these materials.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.100.104509