The role of domain walls on the vortex creep dynamics in unconventional superconducors

TL;DR

This paper explores how domain walls in unconventional superconductors influence vortex behavior, revealing they can trap fractional vortices and act as barriers, affecting magnetic flux and noise characteristics.

Contribution

It demonstrates that domain walls can carry fractional vortices and serve as strong pinning centers, significantly impacting vortex dynamics in multi-component superconductors.

Findings

Domain walls can host fractional flux vortices.

Domain walls act as barriers to vortex motion.

Experimental data supports the theoretical model.

Abstract

We investigate the influence of domain walls on the vortex dynamics in superconductors with multi-component order parameters. We show that, due to their complex structure domain walls can carry vortices with fractional flux quanta. The decay of conventional vortices into fractional ones on domain walls is examined. This decay presents an extraordinarily strong pinning mechanism for vortices and turns domain walls occupied with pinned fractional vortices into efficient barriers for the vortex motion. Therefore, domain walls can act as fences for the flux flow, preventing the decay of the remnant magnetic flux enclosed by them. Furthermore, the consequences of this property of domain walls on the vortex dynamics are discussed in connection with observed noise in the hysteresis cycle, using the Bean model of the critical vortex state. Based on this picture experimental data in the unconventional superconductors UPt$_3$, U$_{1-x}$Th$_x$Be$_{13}$ and Sr$_2$RuO$_4$ are interpreted.