Electrodynamics of granular aluminum from superconductor to insulator: Observation of collective superconducting modes

F. Levy-Bertrand; T. Klein; T. Grenet; O. Dupré; A. Benoît; A. Bideaud; O. Bourrion; M. Calvo; A. Catalano; A. Gomez; J. Goupy; L. Grünhaupt; U. v. Luepke; N. Maleeva; F. Valenti; I. M. Pop; A. Monfardini

doi:10.1103/PhysRevB.99.094506

Electrodynamics of granular aluminum from superconductor to insulator: Observation of collective superconducting modes

F. Levy-Bertrand, T. Klein, T. Grenet, O. Dupré, A. Benoît, A. Bideaud, O. Bourrion, M. Calvo, A. Catalano, A. Gomez, J. Goupy, L. Grünhaupt, U. v. Luepke, N. Maleeva, F. Valenti, I. M. Pop, A. Monfardini

DOI 10.1103/PhysRevB.99.094506 · Physical Review B

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Abstract

We report on a detailed study of the optical response and Tc−ρ phase diagram (Tc being the superconducting critical temperature and ρ the normal state resistivity of the film) of granular aluminum, combining transport measurements and a high resolution optical spectroscopy technique. The Tc−ρ phase diagram is discussed as resulting from an interplay between the phase stiffness, the Coulomb repulsion, and the superconducting gap Δ. We provide direct evidence for two different types of well resolved subgap absorptions, at ω1≃Δ and at Δ≲ω2≲2Δ (decreasing with increasing resistivity).

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Al Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.9	Pressure unresolved	midpoint
Al Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	2.04	Pressure unresolved	midpoint
Al Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	2.17	Pressure unresolved	midpoint
Al Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	2.08	Pressure unresolved	midpoint
Al Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	2.03	Pressure unresolved	midpoint
Al Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.99	Pressure unresolved	midpoint
Al Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.91	Pressure unresolved	midpoint
Al Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.2	Pressure not reported	unknown
NbN Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
InO Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown