Quantum criticality in the electron doped cuprates

We report transport measurements at low temperatures on the electron doped superconductor Pr2-xCexCuO4--delta. Above a certain doping level we observe an abrupt change in the doping dependence of the Hall coefficient along with a significant change in the temperature dependence of the resistivity. At this doping the spin scattering channel in the magnetoresistance vanishes and the temperature dependence of the Hall angle changes. This suggests a quantum phase transition as a function of doping. This transition is most probably due to vanishing of an antiferromagnetic order persisting into the superconducting dome. (c) 2007 Elsevier B.V. All rights reserved.