Tunneling study in granular aluminum near the Mott metal-to-insulator transition

Abstract

We find excellent agreement between tunneling and optical conductivity gap values in superconducting granular aluminum films, up to the metal-to-insulator transition. This behavior, in strong contrast with that recently reported in atomically disordered samples for which the optical gap becomes smaller than the tunneling gap, suggests that disorder is not at the origin of the transition. The large increase seen in the strong coupling ratio and a finite value of the gap at T_c near the metal-to-insulator transition are consistent with a BCS to BEC crossover.

To appear in PRB

References in corpus (8)

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• The Higgs Mode in Disordered Superconductors Close to a Quantum Phase Transition
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Cited by in corpus (5)

• Tuning Superinductors by Quantum Coherence Effects for Enhancing Quantum Computing
• Tuning the superconducting dome in granular aluminum thin films
• Spatial emergence of Off-Diagonal Long-Range Order throughout the BCS-BEC crossover
• Quantum Coherence in Superconducting Vortex States
• Tunneling spectra of unconventional quasi-two-dimensional superconductors