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The role of single-ion excitations in the mixed-spin quasi-1-dimensional quantum antiferromagnet Nd_2BaNiO_5

A. Zheludev·S. Maslov·T. Yokoo·J. Akimitsu·S. Raymond·S. E. Nagler·K. Hirota
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Abstract

Inelastic neutron scattering experiments on Nd2BaNiO5 single-crystals and powder samples are used to study the dynamic coupling of 1-dimensional Haldane-gap excitations in the S=1 Ni2+ -chains to local crystal-field transitions, associated with the rare earth ions. Substantial interference between the two types of excitations is observed even in the 1-dimensional paramagnetic phase. Despite that, the results provide solid justification for the previously proposed ``static staggered field'' model for R2BaNiO5 nickelates. The observed behaviour is qualitatively explained by a simple chain-Random-Phase-Approximation (chain-RPA) model.

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A. Zheludev, S. Maslov, T. Yokoo, J. Akimitsu, S. Raymond, S. E. Nagler, K. Hirota. 1999-10-21. The role of single-ion excitations in the mixed-spin quasi-1-dimensional quantum antiferromagnet Nd_2BaNiO_5. https://arxiv.org/abs/cond-mat/9910335

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