Super-fast dynamics and flow instabilities of superconducting vortices

Date: 12 December 2017

Venue: University of Antwerp - Campus Groenenborger - Room U.244 - Groenenborgerlaan 171 - 2020 Antwerpen (route: UAntwerpen, Campus Groenenborger)

Time: 4:00 PM - 5:00 PM

Organization / co-organization: Condensed Matter Theory

Short description: Condensed Matter Theory seminar presented by Dr Željko Jelić

Abstract
Quantized magnetic vortices driven by electric current determine key electromagnetic properties of superconductors. While the dynamic behavior of slow vortices has been thoroughly investigated, the physics of ultrafast vortices under strong currents remains largely unexplored. In this work, a nanoscale scanning superconducting quantum interference device (SQUID) is used to image vortices penetrating into a superconducting lead (Pb) film at rates of tens of gigahertz (GHz) and moving with velocities of up to tens of km/s, which are not only much larger than the speed of sound but also exceed the pair-breaking speed limit of superconducting condensate.

These measurements reveal formation of mesoscopic vortex channels which undergo cascades of bifurcations as the current and magnetic field increase. Numerical simulations conducted in this work predict metamorphosis of fast Abrikosov vortices into mixed Abrikosov-Josephson vortices at even higher velocities. This work offers an insight into the fundamental physics of dynamic vortex states of superconductors at high current densities, crucial for many applications.



Contact email: lucian.covaci@uantwerpen.be

Link: http://cmt.uantwerpen.be