Magnetic excitations in long-range stripe-ordered Pr2NiO4+δ

Abstract

We report an inelastic neutron scattering study on the magnetic excitations of Pr2NiO4+δ (δ∼0.24±0.01) at T=10 K. Spin stripe ordering becomes pronounced below ∼220 K with an incommensurability ϵ≈0.346, and a strong influence of interstitial oxygen is identified on establishing a long-range spin stripe ordering. Apart from the Goldstone modes emerging from the magnetic satellites (qm), multiple homologous modes are observed along the spin stripe modulation separated by Δqm≈0.076 in reciprocal lattice units, which is interpreted by the internal periodicity of the long-range ordered discommensurated spin stripes.