Shielding current effects on diffraction patterns in the critical current of superconducting quantum interference devices

By a simple schematization of the current distribution in a two-finite-size-junction interferometer, we study the shielding current effects on the diffraction envelope of the interference figure given by the critical current as a function of the applied magnetic field. By this scheme we are able to reproduce the known results in the limit of negligible shielding currents for both conventional interferometers and for those containing one π-junction. For non-negligible values of the circulating current contribution to the superconducting phase in the junctions, we find that the superimposed quantum interference and diffraction patterns suffer a contraction with respect to the horizontal field axis.