Charge stripes and antiferromagnetism in insulating nickelates and superconducting cuprates

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 La2-xSrixNiO4+delta are consistent with the strongly modulated topological-stripe concept. Clues from Nd-doped La2-xSrxCuO4 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. (C) 1998 Elsevier Science Ltd. All rights reserved.