Weak localization and 1/f noise in Nd1.83Ce0.17CuO4+? thin films

We report on electrical transport measurements and voltage-noise analysis in unreduced Nd1.83Ce0.17CuO4+? thin films. At low temperatures ?T?100 K? the resistivity behavior is characterized by a metal-insulator crossover, which in these materials is usually interpreted in terms of weak localization induced by excess oxygen ions randomly distributed on apical impurity sites. The low-frequency voltage-spectral density reveals the presence of different conduction mechanisms in the metallic and in the insulating regions. Standard resistance fluctuations explain well the 1/f noise at temperatures above the resistance minimum while an unusual linear dependence of the 1/f noise on the applied bias current is found at lower temperatures, which could be interpreted as a signature of the occurrence of weak localization.