Hydrodynamic Instability of the Flux-antiflux Interface in Type-II Superconductors

A possible mechanism of the macroturbulence instability observed in fluxline systems during remag-netization of superconductors is proposed. It is shown that when a region with flux is invaded by antiflux the interface can become unstable if there is a relative tangential flux motion. This condition occurs at the interface owing to the anisotropy of the viscous motion of vortices. The phenomenon is similar to the in-stability of the tangential discontinuity in classical hydrodynamics. The obtained results are supported by magneto-optical observations of flux distribution on the surface of a YBCO single crystal with twins.