The spike state in a superconducting needle with a mesoscopic triangular cross section

The spike state is a metastable vortex state, like phase slips and kinematic vortices, that arises and disappears at a single critical field, the one that sets the transition from the normal to the superconducting state. It has been theoretically predicted to exist in the mesoscopic scale (Cadorim et al., 2021 and de Oliveira et al., 2021) within a particular x range, that defines the genuine type-I superconductor. The lifetime of the spike state is obtained here in case of a triangular cross section and found to be six times smaller than that of a circular cross section (de Oliveira et al., 2021). The extrusion process is distinct for these geometries, while in the latter case vortex bubbles are formed and exit the superconductor each one carrying a fraction of the trapped magnetic flux until its total depletion, in the former case the expulsion occurs at a single process. We use the time-dependent Ginzburg-Landau to describe the spike-state.

Automated summary

The spike state is a metastable vortex state that emerges and disappears at a critical field, setting the transition from normal to superconducting state. It is predicted to exist in a specific range at the mesoscopic scale, defining genuine type-I superconductors. The lifetime of the spike state is found to be affected by the geometry, with a triangular cross section having a shorter lifetime compared to a circular cross section.