Supermatching vortex phases in superconducting thin films with antidot lattices

Abstract

We report AC magnetic susceptibility χ and magnetic relaxation measurements on a superconducting WxGe1 − x (x ≈ 0.67) film with an antidot lattice. We find new interstitial vortex phases stablized by collective flux line interactions in a supermatching regime extending well above the saturation field defined by maximal filling of the antidot lattice by flux. Observations of a nonmonotonic field dependence of matching anomalies in χ and a critical depinning angle in relaxation behavior reveal the existence of flux line lattice phases of relatively low stability at certain matching fields.