Magnetic field and sheet-current density of a thin type-II superconducting annulus

We investigate theoretically the sheet-current density and total magnetic field (MF) distribution due to a thin, type-II superconducting annulus sample. We have supposed a washer (with the inner and outer radii a and b) carrying sub-critical currents subject to an applied magnetic field. The sample is an ideal washer with no bulk pinning, under two different situations: (a) when flux is focused into the central hole and net current flowing around the washer is zero but the external field Ha=Ba/μ is on, and (b) in the presence of a potential barrier of geometrical origin. Our calculations show that the net MF is maximum in the near-edge region and in the between is weaker than other areas. Moreover, the effect of geometrical barrier on spatial distribution of the field for several superconducting washers of different radii has been analyzed. At the end, we have shown the behavior of field distribution as external field, Ha , is oriented at any arbitrary angle α.