Magnetic scattering and superconductivity in Nd_1·86Ce_0·14CuO_4-y

Abstract

Nd_1·86Ce_0.14CuO_4-y is superconducting below about 20 K and electrons are considered to be responsible for superconductivity in these materials as in the case of Ln_2-x Ce_x CuO_4-y and Ln_2-x Th_x CuO_4-y. Structurally these materials are not very different from the p-type superconductors La_2-x Sr_x CuO_4-y . In both these types of superconductors, the parent compounds are antiferromagnetically-ordered insulators. The induction of holes or electrons by substitution destroys magnetic interactions and brings about superconductivity. Peng and coworkers have studied the resistivity variation of both superconducting and nonsuperconducting Nd_1·85Ce_0·15CuO_4-y and have found a decrease in resistivity with temperature, obeying a ln T dependence in the superconducting samples. Such a variation was not seen by them in the nonsuperconducting samples. They ascribe the ln T variation seen in their superconducting samples to arise from magnetic scattering of electrons. To study whether such an effect exists, Nd_1·86Ce_0·14CuO_4-y was subjected to various annealing conditions and the resistivity behaviour is presented here. Our results differ from those of Peng et al.