Anomalous saturation of the phase coherence length in underdoped Pr2-xCexCuO4 thin films

We present a quantitative analysis of the magnetoresistance of nonsuperconducting Pr2-xCexCuO4 using fits to two-dimensional weak-localization theory, and extract the temperature dependence of the phase coherence length. This characteristic length scale saturates at low temperatures, correlating with deviations of the in-plane resistivity from rho (xx)proportional to ln(1/T) behavior also observed in these materials. A comparison with Nd1.90Ce0.10CuO4, which shows no saturation, is also presented.