Surface barrier of holes drilled in a type-II superconductor

Holes drilled in a type-II superconductor trap the magnetic flux. Following Clem’s flux pinning model, we consider surface pinning as a mechanism for compressing the magnetic flux in the holes. Estimations of the trapped magnetic flux demonstrate that the holes with the diameter up to 2 mm are advantageous for bulk single-crystal REBCO samples. The REBCO films and tapes can be improved by the holes with diameter smaller than 10 $\mu$m.