Effect of nonstoichiometric disorder on the transport properties of Nd2-xCexCuO4+δ single crystal films

The effect of doping and nonstoichiometric disordering on the anisotropy of resistivity of Nd2-xCexCuO4+δ single crystal films (x=0.12; 0.15; 0.17) with (0 0 1) and (11-bar0) orientations was investigated. We have found that the increase in the nonstoichiometric disorder leads to the growth of resistivity and to the change in the temperature dependence of the in-plane resistivity from ρab(T)∼T2 to ρab(T)∼exp(T/T0)-1/2. For most stoichiometric reduced films the conduction mechanism appears to be different between ab- and c-directions: a combination of in-plane metallic (dρab/dT>0) and out-of-plane nonmetallic (dρc/dT<0) behavior is a real evidence of the 2D-character of the system investigated. The crossover from 2D to 3D was demonstrated to take place with increasing nonstoichiometric disorder