Topological transitions in curved superconductor nanostructures under a strong transport current

We report on a topological transition between the vortex-chain and phase-slip regimes under a strong transport current in an open SC nanotube with a submicron-scale inhomogeneity of the normal-to-the-surface component of the applied magnetic field. When the magnetic field is orthogonal to the axis of the nanotube, which carries the transport current in the azimuthal direction, the induced voltage shows a pulse as a function of the magnetic field. This non-monotonous behavior is attributed to the occurrence of a phase-slip area at such magnetic fields, when the quasi-stationary pattern of vortices changes from single to double chains in each half-tube, followed by re-entrance of the superconducting state with a chain of moving vortices [1]. Fingerprints of vortex and phase-slip patterns experimentally identified in nanohelices are explained by a specific topology of screening superconducting currents [2].

[1] R. O. Rezaev, E. I. Smirnova, O. G. Schmidt, V. M. Fomin, Communications Physics 3, 144 (2020).
[2] R. Córdoba et al., Nano Letters 19, 8597 (2019).