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.
- Granular aluminum
- THz spectroscopy
- Unconventional superconductivity
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Materials Science(all)
- Condensed Matter Physics