Regensburg 2025 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 42: Superconductivity: Tunneling and Josephson Junctions
TT 42.2: Vortrag
Donnerstag, 20. März 2025, 09:45–10:00, H32
Superconductivity of α-Gallium Probed on the Atomic Scale by Normal and Josephson Tunneling — Corinna Fohn1, David Wander1, Danilo Nikolic2,3, Stéphanie Garaudée1, Hervé Courtois1, Wolfgang Belzig3, Claude Chapelier4, Vincent Renard4, and •Clemens B. Winkelmann1,4 — 1Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, F-38000 Grenoble, France — 2Institut für Physik, Universität Greifswald, Felix-Hausdorff-Strasse 6, D-17489 Greifswald, Germany — 3Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany — 4Université Grenoble Alpes, CEA, Grenoble INP, IRIG/DEPHY/PHELIQS, F-38000 Grenoble, France
We investigate superconducting gallium in its α phase using scanning tunneling microscopy and spectroscopy at temperatures down to about 100 mK. High-resolution tunneling spectroscopies using both superconducting and normal tips show that superconducting α-Ga is accurately described by Bardeen-Cooper-Schrieffer theory, with a gap ΔGa = 163 µeV on the α−Ga(112) facet, with highly homogeneous spectra over the surface, including atomic defects and step edges. Using a superconducting Pb tip, we furthermore study the low-bias conductance features of the Josephson junction formed between tip and sample. The features are accurately described by dynamical Coulomb blockade theory, highlighting α−Ga as a possible platform for surface science studies of mesoscopic superconductivity.
Keywords: gallium surface; tunneling spectroscopy; superconductive tunneling; Josephson effect; Dynamical Coulomb blockade