Vortex Interaction with Mesoscopic Surface Cavities in Superconductors

The conformal mapping method is used to study the problem of flux line interaction with surface cavities having cylindrical profile and characteristic size , i.e., within mesoscopic scale, where λ is the penetration length. It is shown that the metastable states are achieved when the dimensions of the surface irregularities do not exceed the coherence length ξ. Our study shows that the surface barrier may vanish at some weak point at which the surface irregularities have mesoscopic scales. On the other hand, a remarkable decrease in the surface barrier occurs when the surface defects size . Our results are compared with the available experimental data and theoretical results.