VORTEX LATTICE PHASE-DIAGRAM OF NB NBZR MULTILAYERS

Multilayer of Nb/NbZr shows an upturn behavior in the parallel upper critical field H(c2\\)(T. In this work, we studied the critical current density J(c) as a function of magnetic field H and of the angle between H and film plane at various temperatures. From the non-monotonic behavior J(c)(H), we found two characteristic fields, H(P) and H(L), above and below the upturn temperature. An analysis with the angular dependence shows that a dimensional crossover in the mixed state and a shift of the order paramater from Nb to NbZr occur at H(P) and H(L), respectively.