The instability of the front of magnetization reversal in anisotropic superconductors

The mechanism of instability of the front of magnetization reversal, i.e., of the boundary separating the regions of existence of vortices with mutually opposite orientations of the magnetic flux (vortex and anti-vortex regions) in type II superconductors, is suggested. The instability is associated with the anisotropy of flow of a vortex fluid, caused by planar defects in the ab plane of high-temperature superconducting single crystals of the 1-2-3 system. The anisotropy of the dynamic properties of vortex matter brings about a jump of the tangential component of the vortex velocity at the front of magnetization reversal; as is known from the classical hydrodynamics of viscous fluids, this leads to the turbulization of flow. It is demonstrated that the hydrodynamic approach to the description of vortex flow helps explain the emergence of a positive increment of the rise of vortex density fluctuations under conditions of a fairly strong anisotropy. The results of magnetooptical investigations of macroturbulence in the vortex system of Y-123 single crystal with a high density of the twinning boundaries lend qualitative support to the theoretical inferences.