Spin Dynamics in an Ordered Stripe Phase

Inelastic neutron scattering has been used to measure the low-energy spin excitations in the ordered charge-stripe phase of La{sub 2}NiO{sub 4+{delta}} with {delta}=0.133 . Spin-wave-like excitations disperse away from the incommensurate magnetic superlattice points with a velocity {approximately}60{percent} of that in the {delta}=0 compound. Incommensurate inelastic peaks remain well resolved up to at least twice the magnetic ordering temperature. Paramagnetic scattering from a {delta}=0.105 sample, which has a N{acute e}el-ordered ground state, shows anomalies suggestive of incipient stripe correlations. Similarities between these results and measurements on superconducting cuprates are discussed. {copyright} {ital 1997} {ital The American Physical Society}