Via magneto-optical imaging of flux density distributions it is shown that the flux-free Meissner state in thin film superconductors can be stabilized towards higher external fields and higher transport currents by using soft magnetic environments. A theoretical understanding of this effect is developed by applying a theoretical model of the Meissner state of thin superconducting strips in magnetic environments. The calculated magnetic field profiles agree well with those derived experimentally for a variety of shielding configurations. It is shown that the current density distributions in the superconducting films are modified by the presence of the soft magnets. Locally, large overcritical values of the current density can be obtained. Moreover, it is demonstrated that magnetic shielding also works for the stabilization of the Meissner phase of grain boundaries in hightemperature superconductors. Since magnetic flux strongly decreases the critical current density across grain boundaries, this effect has particular importance for the improvement and understanding of the current transport in granular superconductors.

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