Vortex states in mesoscopic superconducting squares with engineered pinning

Abstract

Stability of vortex states in mesoscopic superconducting squares with zero, three, and four submicron pinning centers (antidots) is investigated experimentally. By detecting transitions between vortex states using the small-tunnel-junction method, we evaluate the width of magnetic field region over which a particular superconducting state is stabilized. We confirm that the vortex states are significantly stabilized by the existence of antidots. We discuss the effect of the number and positions of antidots on the stability of mesoscopic vortex states.