INTRINSIC PINNING OF VORTICES IN SUPERCONDUCTING NB CU MULTILAYERS GROWN BY MOLECULAR-BEAM EPITAXY/

Magnetic moment measurements by means of a torque magnetometer on niob ium/copper multilayers grown in a molecular beam epitaxy system show a well-defined series of maxima at specific field strengths. They are o bserved only at small angles between the applied magnetic field and th e superconducting layers. The fields at which they occur depend on the total thickness of the multilayer. The results can be explained by co nsidering step by step how vortices enter the film when a field parall el to the film is continuously increased.