Regensburg 2025 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 5: Superconductivity: Properties and Electronic Structure I

TT 5.10: Talk

Monday, March 17, 2025, 12:00–12:15, H36

Unique electronic transport characteristics in superconducting MgB₂ films — •Clemens Schmid¹, Markus Gruber¹, Corentin Pfaff², Theo Courtois², Anton Pokusinskyi³, Alexander Kasatkin⁴, Karine Dumesnil², Stephane Mangin², Thomas Hauet², and Oleksandr Dobrovolskiy³ — ¹Faculty of Physics and Vienna Doctoral School in Physics, University of Vienna, Austria — ²Institute Jean Lamour, Université de Lorraine-CNRS, Nancy, France — ³Cryogenic Quantum Electronics, EMG and LENA, Technische Universität Braunschweig, Germany — ⁴G.V. Kurdyumov Institute for Metal Physics, NAS Ukraine, Kyiv, Ukraine

Maximizing the velocity of Abrikosov vortices in superconductors and characterizing the associated energy relaxation times is essential for possible applications like single photon detectors. Here, we investigate the current-voltage curves of MgB₂, a material whose thin film structures remain superconducting at temperatures up to 30 K. Furthermore, capabilities of a single photon response have been observed previously in MgB₂ films. Our experiments reveal peculiar shapes of the current-voltage curves, showing multiple steps in their transitions to the normal state. While the microscopic mechanisms underlying these steps are a topic of current debates, one explanation could imply the occurrence of composite and fractional vortices associated with the two-band nature of the superconductivity in MgB₂, a property which is in-line with the presence of two slopes in the temperature-magnetic-field phase diagram. We compare our findings across multiple layered structures and for varying thicknesses of the MgB₂.

Keywords: Superconductivity; MgB2; Abrikosov Vortex Dynamics; Fluxonics