Stripe correlations of spins and holes in cuprate superconductors

It is argued that the stripe order of spins and holes found in La_2–xSr_xNiO₄+ is a useful model for spin and charge correlations in La_2–xSr_xCuO₄. A direct connection with the cuprates is now established by neutron diffraction evidence for stripe order in La_1.6–xNd_0.4Sr_xCuO₄ withx=0.12. The experimental work has stimulated new theoretical ideas.It is a pleasure to acknowledge my collaborators, especially J. D. Axe, D. J. Buttrey, N. Ichikawa, J. E. Lorenzo, Y. Nakamura, V. Sachan, B. J. Sternlieb, P. Wochner, and S. Uchida. Work at Brookhaven is supported by the Division of Materials Sciences, U.S. Department of Energy, under Contrast No. DE-AC02-76CH00016.