Hole Doping Effect on 2D Spin Correlations in La2NiO4+δ

Abstract
Quasielastic neutron scattering experiments from La 2 NiO 4+δ revealed a substantial hole doping effect on the 2 dimensional spin correlations. Thermal evolution of correlation length clearly shows the reduction of the exchange stiffness constant by hole doping, which is in marked contrast to that of La 2 CuO 4+δ . The present result is reflected by the hole character in La 2 NiO 4+δ , which is different from that in the cuprate.