Two quasi-one-dimensional S=1 quantum antiferromagnetic materials, PbNi2V2O8 and SrNi2V2O8, are studied by inelastic neutron scattering on powder samples. A simple model Hamiltonian is proposed for the two systems and used to analyze the data. Quantitative information on in-chain and interchain interactions obtained from this analysis is discussed in the context of qualitatively different ground-state properties: magnetic long-range order in SrNi2V2O8 and disordered ``spin liquid'' Haldane-gap state in PbNi2V2O8.     «

Two quasi-one-dimensional S=1 quantum antiferromagnetic materials, PbNi2V2O8 and SrNi2V2O8, are studied by inelastic neutron scattering on powder samples. A simple model Hamiltonian is proposed for the two systems and used to analyze the data. Quantitative information on in-chain and interchain interactions obtained from this analysis is discussed in the context of qualitatively different ground-state properties: magnetic long-range order in SrNi2V2O8 and disordered ``spin liquid'' Haldane-gap s...     »