ELASTIC FLUX-CREEP IN A SM1.85CE0.15CUO4-Y SINGLE-CRYSTAL

Current-voltage V(I) characteristics, and the magnetoresistivity rho(T H) have been measured for a SM1.85Ce0.15CuO4-y Single crystal in magne tic fields parallel to the c axis. We have found that a well-defined l ine H(T) exists in the H-T plane which separates Ohmic from non-Ohmic behavior. Below H(T), the V(I) curves are described by V/I is simila r to exp[-U(T,H,I)/k(B)T] where U(T,H,I) is similar to U(T,H)ln(I0/I). From the analysis of the V(I) characteristics the effective flux-cree p energy barriers at any temperature and magnetic field are extracted. These data are used to calculate the magnetoresistivity curves rho(TH ) which compare very favorably with the experimental data over less-th an-or-equal-to 80%rho(n) of the resistive transition. The significance of the observed U(I) is similar to -lnI dependence is discussed.