Condensed-Matter Physics & Materials Science Seminar
"From YBCO nanowires and Josephson junctions to superconducting hybrids:properties and macroscopic quantun phenoma"
Presented by Francesco Tafuri, CNR-SPIN and Seconda Università di Napoli, ITALY, Italy
Tuesday, July 10, 2012, 2:00 pm — Bldg. 480 conference room
High critical temperature superconductors (HTS) nano-sized systems ranging from YBaCuO nano-junctions and nano-channels to superconducting hybrid systems incorporating nanowires, have been realized and characterized exhibiting a series of remarkable properties.
YBCO nanowires of widths down to 50 nm operate up at 80 K with critical current densities just a few times smaller than the depairing current. Escape dynamics has been measured in top-down and “self-assembling” bottom-up nano-Josephson junctions characterized by different levels of dissipation. By measuring switching process from the zero voltage to the finite voltage branch in the current-voltage (I-V) characteristics, their quantum signature encoded in macroscopic quantum phenomena has been extracted. Novel insights on the interplay between coherence and dissipation in the moderately damped regime have been achieved, of interest for various quantum hybrid architectures. In these junctions phase diffusion processes coexist with thermal activation and macroscopic quantum tunneling. Similar studies have been comparatively carried out on NbN Josephson junctions.
Results encourage the integration of HTS nanostructures in hybrid systems functional to various applications and in quantum cells.
Hosted by: Ivan Bozovic
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