Origin of the anomalous low temperature upturn in resistivity in the   electron-doped cuprates
  The temperature, doping and field dependences of the magnetoresistance (MR) in Pr_(2-x)Ce_(x)CuO_(4-delta) films are reported. We distinguish between orbital MR, found when the magnetic field is applied perpendicular to the ab planes, and the nearly isotropic spin MR. The latter, the major MR effect in the superconducting samples, appears in the region of the doping-temperature phase diagram where d(rho)/dT<0, or an upturn in the resistivity appears. We conclude that the upturn originates from spin scattering processes. 
Y. Dagan, A. Biswas, M. C. Barr, W. M. Fisher, and R. L. Greene