Magnetic Neutron Scattering Study of Nd$_{1.85}$Ce$_{0.15}$Cu$_{1-y}$Ni$_{y}$O$_{4}$ Single Crystals

In order to arrive at a deeper understanding of the interplay between superconductivity and magnetism in the high-temperature superconductors, it is of interest to study the effects of impurity-doping on the copper site. A large body of work along these lines exists for hole-doped materials, yet relatively little is known about the effects of such impurities on the prototypical electron-doped material (Nd,Ce)$_{2}$CuO$_{4}$. In previous work, paramagnetic dopants (Ni, Fe) were shown to lower T$_{c}$ much more abruptly than non-magnetic ones (Zn). We grew large single crystals of Nd$_{1.85}$Ce$_{0.15}$Cu$_{1-y}$Ni$_{y}$O$_{4}$ using the traveling-solvent floating-zone technique and characterized our samples using SQUID magnetometry and DC transport measurements. Here we report on neutron scattering results for the spin correlations as a function of nickel concentration and temperature for superconducting (y $<$ 0.01) and non-superconducing (y$>$ 0.01) compositions.