Flux penetration in a superconducting strip with an edge indentation

The flux penetration near a semicircular indentation at the edge of a thin superconducting strip placed in a transverse magnetic field is investigated. The flux front distortion due to the indentation is calculated numerically by solving the Maxwell equations with a highly nonlinear $E(j)$ law. We find that the excess penetration Δ can be significantly (~50%) larger than the indentation radius r₀, in contrast to a bulk superconductor in the critical state where Δ=r₀. It is also shown that the flux creep tends to smoothen the flux front, i.e., reduce Δ. The results are in very good agreement with magneto-optical studies of flux penetration into an YBa₂Cu₃Oₓ film having an edge defect.