Charge stripes and antiferromagnetism in insulating nickelates and superconducting cuprates

Abstract Neutron and X-ray scattering studies have provided strong evidence for coupled spatial modulations of charge and spin densities in layered nickelates and cuprates. The accumulated results for La 2− x Sr ix NiO 4+δ are consistent with the strongly modulated topological-stripe concept. Clues from Nd-doped La 2− x Sr x CuO 4 suggest similar behavior for the cuprates. The experimental results are summarized, and features that conflict with an interpretation based on a Fermi-surface instability are emphasized. A rationalization for the differences in transport properties between the cuprates and nickelates is given.