The resistive anomaly and upward curvature of the perpendicular upper critical field in non-homogeneous superconductors

A peak in the resistance versus temperature measurements, just above T-C, has been observed for perforated superconducting Nb/CuMn multilayers. The peak is present in zero magnetic field and its height becomes smaller as the perpendicular field is increased. In addition, the perpendicular critical magnetic field versus temperature curve shows an upward positive curvature. By considering a simple concentrated constant-equivalent circuit we have reproduced the observed resistive transitions and the upper perpendicular critical magnetic field behaviour.