Vortex Quantum Nucleation and Tunneling in Superconducting Thin Films: Role of Dissipation and Periodic Pinning

TL;DR

This paper explores quantum vortex decay mechanisms in superconducting thin films, emphasizing how dissipation and periodic pinning influence vortex tunneling, nucleation rates, and resulting resistance at high current densities.

Contribution

It provides a detailed analysis of quantum vortex decay processes, highlighting the impact of dissipation and engineered pinning on supercurrent stability and vortex dynamics in superconducting films.

Findings

Vortex tunneling and nucleation rates depend rapidly on current density.

Edge-tunneling is favored over bulk nucleation under certain conditions.

Periodic pinning induces current-oscillations and affects vortex pair-production rates.

Abstract

We investigate the phenomenon of decay of a supercurrent in a superconducting thin film in the absence of an applied magnetic field. The resulting zero-temperature resistance derives from two equally possible mechanisms: 1) quantum tunneling of vortices from the edges of the sample; and 2) homogeneous quantum nucleation of vortex-antivortex pairs in the bulk of the sample, arising from the instability of the Magnus field's ``vacuum''. We study both situations in the case where quantum dissipation dominates over the inertia of the vortices. We find that the vortex tunneling and nucleation rates have a very rapid dependence on the current density driven through the sample. Accordingly, whilst normally the superconductor is essentially resistance-free, for the high current densities that can be reached in high-$T_c$ films a measurable resistance might develop. We show that edge-tunneling appears favoured, but the presence of pinning centres and of thermal fluctuations leads to an enhancement of the nucleation rates. In the case where a periodic pinning potential is artificially introduced in the sample, we show that current-oscillations will develop indicating an effect specific to the nucleation mechanism where the vortex pair-production rate, thus the resistance, becomes sensitive to the corrugation of the pinning substrate. In all situations, we give estimates for the observability of the studied phenomena.