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TT: Fachverband Tiefe Temperaturen

TT 14: Superconductivity: Properties and Electronic Structure

TT 14.12: Vortrag

Montag, 9. März 2026, 18:00–18:15, HSZ/0103

Crystal Structure Effects on Vortex Dynamics in Superconducting MgB₂ Films — •Clemens Schmid¹, 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, Vandoeuvre-lès-Nancy, France — ³Cryogenic Quantum Electronics, EMG and LENA, Technische Universität Braunschweig, Germany — ⁴G. V. Kurdyumov Institute for Metal Physics, NAS Ukraine, Kyiv, Ukraine

MgB₂ offers one of the highest critical temperatures among non-cuprate superconductors. However, its dynamic phase diagram at high vortex velocities remains unexplored, and the film structure and interface quality are expected to affect the current-driven resistive transition. Here, we investigate two different structures incorporating MgB₂ thin films sputtered on sapphire (Al₂O₃) substrates. The difference between the films is in the inclusion of an additional MgO layer between the substrate and MgB₂, resulting in a single crystal structure, as opposed to an MgO-free textured one. We find that the activation energy for vortex motion is a factor of two higher for the single-crystal film. Current-voltage measurements reveal multiple jumps, suggesting that the transition to the normal state is driven by the formation of normal domains. Additionally, a lower instability current in the textured film suggests less efficient heat removal, which agrees with the results of an HRTEM inspection of the film-substrate interface.

Keywords: Superconductivity; MgB2; Vortex Dynamics; Thin Films