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Journal of Low Temperature Physics

, Volume 179, Issue 1–2, pp 83–89 | Cite as

Signatures of Unconventional Superconductivity in Granular Aluminum

  • N. BacharEmail author
  • U. S. Pracht
  • E. Farber
  • M. Dressel
  • G. Deutscher
  • M. Scheffler
Article

Abstract

We present measurements of the complex transmission of superconducting granular aluminum thin films in the THz optical range. We discuss the dynamical conductivity and temperature-dependent energy gap of two films of different granular coupling. While the film of well-coupled grains follows the predictions for a conventional BCS superconductor, signatures of enhanced absorption are found at sub-gap frequencies when coupling is decreased. We discuss possible explanations which might account for the observed deviations from BCS theory.

Keywords

Unconventional superconductivity Granular aluminum  THz spectroscopy 

Notes

Acknowledgments

We acknowledge fruitful discussions with N. Trivedi, L. Benfatto, D. Sherman, A. Frydman, and B. Gorshunov. N.B. and U.S.P. contributed equally to this work. In addition, U.S.P. is greatful for financial support of the Studienstiftung des deutschen Volkes.

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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • N. Bachar
    • 1
    • 3
    Email author
  • U. S. Pracht
    • 2
  • E. Farber
    • 1
  • M. Dressel
    • 2
  • G. Deutscher
    • 3
  • M. Scheffler
    • 2
  1. 1.Laboratory for Superconductivity and Optical SpectroscopyAriel UniversityArielIsrael
  2. 2.Physikalisches InstitutUniversität StuttgartStuttgartGermany
  3. 3.Raymond and Beverly Sackler School of Physics and AstronomyTel Aviv UniversityTel AvivIsrael

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