Quantitative analysis of the critical current due to vortex pinning by   surface corrugation
  The transport critical current of a Niobium (Nb) thick film has been measured for a large range of magnetic field. Its value and variation are quantitatively described in the framework of the pinning of vortices due to boundary conditions at the rough surface, with a contact angle well explained by the spectral analysis of the surface roughness. Increasing the surface roughness using a Focused Ion Beam results also in an increase of the superficial critical current. 
Alain Pautrat, J. Scola, C. Goupil, Ch. Simon, C. Villard, B.   Domenges, Y. Simon, Ch. Guilpin, L. Mechin