Imaging super-fast vortex dynamics and mapping pinning potential of individual vortices

Using a novel scanning nanoSQUID-on-tip the displacement trajectories of single driven vortices are imaged with sub-Angstrom spatial resolution revealing the complex internal potential structure of individual pinning centers and the hysteretic switching between cellular vortex trajectories [1]. At higher driving currents super-fast vortex dynamics is found in which individual vortices penetrate into a superconducting film at rates of tens of GHz and move at velocities up to tens of km/s that greatly exceed the pair-breaking speed limit of the Cooper-pair condensate, while preserving their integrity as topological defects [2]. Instead of random motion of repelling vortices, striking formation of vortex channels is observed that undergo cascades of branching instabilities and bifurcations as the field and current are increased. The work offers a new insight into the fundamental physics of vortex pinning and of the microscopic instabilities of vortex resistive state in superconductors at high currents, crucial for many applications.

[1] L. Embon, Y. Anahory, A. Suhov, D. Halbertal, J. Cuppens, A. Yakovenko, A. Uri, Y. Myasoedov, M.L. Rappaport, M.E. Huber, A. Gurevich, and E. Zeldov, Probing dynamics and pinning of single vortices in superconductors at nanometer scales, Scientific Reports 5, 7598 (2015).
[2] L. Embon, Y. Anahory, Z. L. Jelic, E. O. Lachman, Y. Myasoedov, M. E. Huber, G. P. Mikitik, A. V. Silhanek, M. V. Milosevic, A. Gurevich, and E. Zeldov, Imaging of super-fast dynamics and flow instabilities of superconducting vortices, Nature Commun. 8, 85 (2017).