Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 19: Superconductivity: Poster Session
TT 19.2: Poster
Montag, 7. März 2016, 15:00–18:00, Poster D
Co-sputtered MoRe as carbon nanotube growth-compatible superconductor — •Karl Götz, Stefan Blien, Peter Stiller, Ondrej Vavra, Thomas Mayer, Thomas Huber, Thomas Meier, Matthias Kronseder, Christoph Strunk, and Andreas Hüttel — Institute for Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
Molybdenum rhenium alloys exhibit superconducting transition temperatures up to 15 K as well as high critical current densities. In addition, the thin films are stable under typical carbon nanotube CVD growth conditions, i.e., a hydrogen/methane atmosphere at 900 ∘C, and form good contacts in nanotube overgrowth. This makes them predestined for experiments integrating “ultraclean” carbon nanotube devices into coplanar radiofrequency circuits, towards quantum nano-electromechanics and information processing. MoRe thin films are deposited via co-sputtering of two separate targets. The resulting thin film composition and its controllability is verified via XPS spectroscopy both before and after undergoing nanotube growth conditions. The effects of the high temperature process on surface oxides, carbon content, superconducting critical temperature, magnetic field, and current are characterized. Selecting an optimized alloy composition, we define coplanar waveguide resonators, demonstrating resonant behaviour after CVD at f≈ 3 … 4 GHz and up to Qi≈5000. Modelling device properties via Mattis-Bardeen theory combined with substrate two-level systems leads to good agreement with the data.