Transport and localization in Nd2-xCexCuO4-y crystals at low doping.

Abstract

We report in-plane transport properties of ${\mathrm{Nd}}_{2\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Ce}}_{\mathit{x}}$${\mathrm{CuO}}_{4\mathrm{\ensuremath{-}}\mathit{y}}$ crystals prepared in low-doped (x\ensuremath{\sim}0.01--0.11), nonsuperconducting compositions. The large negative Hall coefficient ${\mathit{R}}_{\mathit{H}}$ and thermopower S in these samples confirm the presence of a small density of n-type carriers. At low T we find a highly anisotropic negative magnetoresistance which, together with the behavior of \ensuremath{\rho}, S, and ${\mathit{R}}_{\mathit{H}}$, demonstrates two-dimensional weak localization of these carriers occurring as Ce content decreases. Analysis of the magnetoresistance data reveals an anomalously weak T dependence of the electron inelastic-scattering rate 1/${\mathrm{\ensuremath{\tau}}}_{\mathit{i}}$.