Within the VMG E-COST-GRANT-CA16218-1f6dba72, M. Sc. Igor Bogush (State University of Moldova) under supervision of Prof. Dr. Vladimir Fomin (the Leibniz IFW Dresden) developed and optimized an algorithm for superconductivity simulations in novel 3D nanoarchitectures using NVIDIA CUDA technology for GPUs based on Time-Dependent Ginzburg-Landau equation. Using the developed algorithm, they revealed how the topological transitions between vortex-chain and phase-slips regimes in curved superconductor nanomembranes are governed by the geometry and the external stimuli . They investigated current-voltage characteristics in niobium open tubes (Fig. 1a) as a function of the applied external magnetic field and transport current (Fig. 1b, c, d). They predicted a novel hysteresis effect in the current-voltage characteristic (Fig. 1b) owing to a barrier between vortex-chain and phase-slips regimes. They found that an abrupt switch-on of the transport current or the magnetic field triggers the transition from the vortex-chain to the phase-slip regime, as compared to the gradual switch-on (Figs. 1c,d).
Figure 1: Open Nb nanotube embedded into the heatsink (a). The hysteresis effect for the average voltage induced at different values of the external magnetic field (in mT) for . (b) Average voltage induced at different values of the transport current (in GA/m2) for in the magnetic field B, which is switched on gradually (c) and abruptly (d), reflects vortex-chain and phase-slip regimes, correspondingly. Insets: patterns of the complex order parameter (white regions encode superconducting state; colors encode phase of the superconducting order parameter). (After .) I. Bogush, V. M. Fomin, arXiv:2110.12745v1 [cond-mat.supr-con] (2021).