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

We investigate the influence of domain walls an the vortex dynamics in supe rconductors with multi-component order parameters. We show that, due to the ir complex structure domain walls can carry vortices with fractional flux q uanta. The decay of conventional vortices into fractional ones on domain wa lls is examined. This decay presents an extraordinarily strong pinning mech anism for Vortices and turns domain walls occupied with pinned fractional V ortices into efficient barriers for the vortex motion. Therefore, domain wa lls can act as fences for the flux flow, preventing the decay of the remnan t magnetic flux enclosed by them. Furthermore, the consequences of this pro perty of domain walls on the vortex dynamics are discussed in connection wi th observed noise in the hysteresis cycle, using the Bean model of the crit ical vortex state. Based on this picture experimental data in the unconvent ional superconductors UPt3, U1-xThxBe13 and Sr2RuO4 are interpreted.