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TT: Fachverband Tiefe Temperaturen
TT 16: Poster Session Superconductivity, Cryogenic Particle Detectors, Cryotechnique
TT 16.2: Poster
Montag, 16. März 2020, 15:00–19:00, P2/EG
Terahertz electrodynamics of low-temperature-grown granular aluminum — •Mehmet Ali Nebioglu, Alessandro D’Arnese, Martin Dressel, and Marc Scheffler — 1.Physikalisches Institut, Universität Stuttgart, Germany
Granular aluminum exhibits superconducting properties that can be tuned by its microscopic structure, in particular the size of the aluminum grains and the thickness of the aluminum-oxide barriers that separate the grains. This makes granular aluminum interesting for both fundamental studies of relevant superconducting energy scales and for applications. Terahertz (THz) spectroscopy is a powerful tool to study these energies via the frequency-dependent response of superconducting films that can be probed in transmission measurements, and it also gives access to superconducting collective modes [1, 2].
We study the THz response of granular aluminum films that are grown at cryogenic temperatures (down to the 4He regime) and thus can exhibit substantial enhancement of Tc compared to room-temperature-grown films. We present the complex optical conductivity and we determine superconducting energy gap and superfluid stiffness. We compare these results to BCS predictions and to previous studies on granular aluminum films grown at higher temperatures [1, 3].
[1] Uwe S. Pracht et al., Phys. Rev. B 93, 100503 (2016).
[2] Uwe S. Pracht et al., Phys. Rev. B 96, 094514 (2017).
[3] Aviv Glezer Moshe et al., Phys. Rev. B 99, 224503 (2019).