The universal behaviour of the magnetic excitations in high-temperature superconductors is described in a model with static stripes retaining only the localized spin degrees of freedom. The stripes are represented by a model of coupled two-leg spin ladders. We start from the results obtained previously by continuous unitary transformations for an isolated spin ladder. A quantitative description of neutron scattering data is reached, using a model for a single cuprate layer with well established values of the exchange coupling constants. The neutron resonance peak is explained in terms of a saddle point in the dispersion of the magnetic excitations. Here we make predictions for bilayer systems with in-phase or out-of-phase stripe correlations. The results may serve as a guide for future experimental analyses.
@article{arxiv.cond-mat/0502460,
title = {Magnetic Excitations in Bilayer High-Temperature Superconductors with Stripe Correlations},
author = {G. S. Uhrig and K. P. Schmidt and M. Grüninger},
journal= {arXiv preprint arXiv:cond-mat/0502460},
year = {2007}
}