Abstract
An experimental determination of the mean vortex velocity in superconductors mostly relies on the measurement of flux-flow resistance with magnetic field, temperature, or driving current. In the present work we introduce a method combining conventional transport measurements and a frequency-tuned flashing pinning potential to obtain reliable estimates of the vortex velocity. The proposed device is characterized using the time-dependent Ginzburg-Landau formalism, where the velocimetry method exploits the resonances in mean vortex dissipation when temporal commensuration occurs between the vortex crossings and the flashing potential. We discuss the sensitivity of the proposed technique on applied current, temperature and heat diffusion, as well as the vortex core deformations during fast motion.
Highlights
The resistive state of superconducting thin films in an external magnetic field and applied transport current is a consequence of the dissipative motion of vortices[1,2]
Quasi-periodic behavior of the V(τ) characteristics shown in Fig. 2 corroborates that, where in each consecutive stroboscopic state an additional vortex participates in the dynamics, relating the order of the resonance n exactly to the number of crossing vortices while the channel is open
We discuss the thermal effects related to the resonances and the vortex behavior through V(τ) characteristics shown in Fig. 5 for the same current used in Fig. 4, in the case when: (a) bath temperature is varied and (b) maximal temperature in the channel is varied
Summary
The resistive state of superconducting thin films in an external magnetic field and applied transport current is a consequence of the dissipative motion of vortices[1,2]. In this paper we devise a concept for vortex velocity measurement stemming from the stroboscopic states in a superconductor with a dynamic pinning landscape We show that this approach, in which we take into account spatial and temporal heat dissipation, is able to precisely capture vortex velocities, even very high ones, and thereby discern different vortex phases at the crossover from Abrikosov to Josephson ones, each of which are tunable either by external modulation, or by temperature, current, or magnetic field
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