Magnetic-flux penetration and critical currents in superconducting strips with slits

We theoretically investigate transport-current-induced magnetic-flux penetr ation into superconducting strip lines with slits. Even when the individual strips have no bulk pinning, geometrical barriers prevent penetration of m agnetic flux into the innermost strips while flux quasistatically penetrate s into the outermost slits. The critical current of strip lines with 2N sli ts at zero applied magnetic field is found to be enhanced by a factor of (N + 1)(1/2) above that of a single strip line without slits. Under suitable conditions, a domelike flux distribution due to the geometrical barrier can appear in the individual strips even in the absence of an applied magnetic field.