FLUX PHASES IN SUPERCONDUCTING ANTIDOT ARRAYS - INFLUENCE OF THE ANTIDOT SIZE

We have studied the magnetization (M(H)) and critical currents (I-c(H) ) of superconducting a-W0.67Ge0.33 films with a square array of submic ron holes (antidots) having a fixed periodicity of 1 mu m for differen t antidot sizes. Pronounced anomalies are present in M(H) and I-c(H) w hen the external magnetic field is equal to a matching field. For smal l antidot sizes the nucleation of Abrikosov vortices at interstitial p ositions occurs, leading to a drastic reduction of the critical curren ts. For large antidots, a crossover to a wire network regime is observ ed.