  Superconducting Nb thin films with rectangular arrays of submicron antidots
have been systemically investigated by transport measurements. In low fields,
the magnetoresistance curves demonstrate well-defined dips at integral and
rational numbers of flux quanta per unit cell, which corresponds to a
superconducting wire network-like regime. When the magnetic field is higher
than a saturation field, interstitial vortices interrupt the collective
oscillation in low fields and form vortex sublattice, where a larger magnetic
field interval is observed. In higher fields, a crossover behavior from the
interstitial sublattice state to a single-loop-like state is observed,
characterized by oscillations with a period of $\Phi_0/\pi r_{eff}^2$,
originating from the existence of edge superconducting states with a size
$r_{eff}$ around the antidots.

Mesoscale and Nanoscale Physics