Measurements of thermoelectric power (TEP) and Hall coefficient ${(R}_H)$ are carried out on ${\mathrm{Pr}}_{2-x}{\mathrm{Ce}}_x{\mathrm{CuO}}_{4-\delta }$ epitaxial films to probe the mechanism of charge transport in the absence of superconductivity. In the underdoped $\mathrm{}(x=0.13\mathrm{})\mathrm{}$ and optimally doped $\mathrm{}(x=0.15\mathrm{})\mathrm{}$ samples, the TEP shows a $\ln \mathrm{}(1/T)\mathrm{}$ dependence and the $R_H$ remains constant in the temperature range accessed by suppressing superconductivity. These observations and the behavior of the in-plane resistivity indicate weak localization of charge carriers on the ${\mathrm{CuO}}_2$ planes. The TEP and $R_H$ of the overdoped sample mimic metallic transport. This, combined with the evidence for hole and electron charge carriers, which may exist on different planes of the unit cell, suggests that the metallic transport in the overdoped samples is a consequence of a three-dimensional charge distribution.

• Received 9 October 2001

DOI:https://doi.org/10.1103/PhysRevB.65.100517