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Structure first approach to low-loss superconducting materials development

April 2, 2018 - 11:00am
Christopher Richardson


Many superconductors are generally forgiving of modest concentrations of chemical impurities and insensitive to microstructure.  However, reducing the superconducting loss tangent of planar devices to less than 1e-6 requires attention to material synthesis and device fabrication.  This material focused seminar will explore the path towards optimizing the structure of two superconducting thin film materials and related correlations with superconducting loss.

Single-crystal, thin-film aluminum grown via molecular beam epitaxy on silicon substrates exhibits an atomically abrupt metamorphic Al-Si interface.  Characterization of the interface purity and atomic resolution imaging of the structured semi-coherent interface are correlated with low-power internal quality factors of quarter-wave coplanar waveguide resonators that are near 1e6.

Polycrystalline, thin film titanium nitride grown with plasma assisted molecular beam epitaxy on silicon substrates exhibits significantly more crystalline disorder and higher levels of impurities.  Nonetheless, TiN superconducting resonators demonstrate internal quality factors over 1M at low-powers and approach 10M at high-powers. 

Host: Mohammad Hafezi

Atlantic 2400
College Park, MD 20742