Thermopower and Hall conductivity in the magnetic-field-driven normal state of Pr_2-xCe_xCuO_4-δ superconductors

Abstract

Measurements of thermoelectric power (TEP) and Hall coefficient (R_H) are carried out on Pr_2-xCe_xCuO_4-δ epitaxial films to probe the mechanism of charge transport in the absence of superconductivity. In the underdoped (x=0.13) and optimally doped (x=0.15) samples, the TEP shows a ln(1/T) 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 CuO₂ 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.