Dispersion of Magnetic Excitations in the Cuprate La(2)CuO(4) and CaCuO(2) Compounds Measured Using Resonant X-Ray Scattering

By resonant inelastic x-ray scattering in the soft x-ray regime we probe the dynamical multiple-spin correlations in the antiferromagnetic cuprates La(2)CuO(4) and CaCuO(2). High resolution measurements at the copper L(3) edge allow the clear observation of dispersing bimagnon excitations. Theory based on the ultrashort core-hole lifetime expansion fits the data on these coherent spin excitations without free parameters.