Melting of the vortex lattice in perforated Nb/CuMn multilayers

Transport properties of Nb/CuMn multilayers with a regular array of antidots have been measured at different temperatures in the presence of external perpendicular magnetic fields. Two series of samples, which differ for the Mn percentage, for the diameter, and for distance of the antidots have been analyzed. In both the series, hysteresis in current–voltage characteristics has been observed, which disappears when approaching the upper critical magnetic field. We have related the onset of this hysteresis to the presence of an irreversibility line in the H– T plane, due to the quantum melting of the vortex lattice.