Fragmentation of Fast Josephson Vortices and Breakdown of Ordered States by Moving Topological Defects

TL;DR

This paper investigates how fast-moving Josephson vortices become unstable due to Cherenkov radiation, leading to vortex-antivortex pair creation and breakdown of ordered superconducting states, with implications for electronic applications.

Contribution

It reveals the instability mechanism of moving Josephson vortices driven by strong currents, showing how they generate vortex-antivortex pairs and disrupt global order.

Findings

Vortices become unstable at high velocities due to Cherenkov radiation.

Vortex-antivortex pairs form and separate, creating dissipative regions.

Single vortices can switch entire junctions to resistive states at low currents.

Abstract

Topological defects such as vortices, dislocations or domain walls define many important effects in superconductivity, superfluidity, magnetism, liquid crystals, and plasticity of solids. Here we address the breakdown of the topologically-protected stability of such defects driven by strong external forces. We focus on Josephson vortices that appear at planar weak links of suppressed superconductivity which have attracted much attention for electronic applications, new sources of THz radiation, and low-dissipative computing. Our numerical simulations show that a rapidly moving vortex driven by a constant current becomes unstable with respect to generation of vortex-antivortex pairs caused by Cherenkov radiation. As a result, vortices and antivortices become spatially separated and accumulate continuously on the opposite sides of an expanding dissipative domain. This effect is most pronounced in thin film edge Josephson junctions at low temperatures where a single vortex can switch the whole junction into a resistive state at currents well below the Josephson critical current. Our work gives a new insight into instability of a moving topological defect which destroys global long-range order in a way that is remarkably similar to the crack propagation in solids.