INFLUENCE OF MAGNETIC-FIELD ON THE SUPERCONDUCTING TRANSITION IN A ND1.82CE0.18CUO4-DELTA FILM

The temperature and magnetic-field dependences of the resistivity rho and Hall effect R (j parallel to ab, B parallel to c) in a Nd1.82Ce0.1 8CuO4-delta single crystal film (T-c=6 K) is investigated at temperatu res 1.4 less than or equal to T less than or equal to 20 K and magneti c fields 0 less than or equal to B less than or equal to 5.5 T. At the lowest temperature T=1.4 K the resistive state (exhibiting resistivit y and the Hall effect) arises in a magnetic held B=0.5 T. A transition to the normal state is completed at B(c2)similar or equal to 3 T, whe re the Hall coefficient becomes nearly constant. The negative magnetor esistance due to the weak-localization effect in the normal state is o bserved for B>3 T. The nonmonotonic behavior and the inversion of the sign of R(B) in the mixed state are explained in a reasonable way by t he flux-flow model with the effect of pinning taken into account. (C) 1996 American Institute of Physics.