Two-dimensional character of the magnetoresistance in Nd_1.85Ce_0.15CuO_4-δ thin films

The magnetoresistance of in situ thin films of Nd1.85Ce0.15CuO4-δ in a metallic but non-superconducting state due to excess oxygen was measured at low temperatures in transverse fields. At 4.2 K and for fields perpendicular to the CuO2 planes, we find a reduction of the resistance by 16% in a field of 13.2T, with no sign of saturation. The effect in parallel fields is much smaller, and the field dependence is different. The perpendicular field data are fit by the theory of weak localization in two dimensions. The fits indicate a low spin-orbit scattering rate. In situ superconducting samples were measured in a perpendicular field up to 30 T, and also show negative magnetoresistance and an upturn of the normal state resistance at low temperature. © 1991.