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Magnetic ordering, spin waves, and Haldane gap excitations in (Nd_x Y_{1-x})_2 Ba Ni O_5 linear-chain mixed-spin antiferromagnets

T. Yokoo·S. Raymond·A. Zheludev·S. Maslov·E. Ressouche·I. Zaliznyak·R. Erwin·M. Nakamura·J. Akimitsu
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Abstract

Linear-chain nickelates with the composition (Nd_x Y_{1-x})_2 Ba Ni O_5 (x=1, x=0.75, x=0.5, and x=0.25) are studied in a series of neutron scattering experiments. Powder diffraction is used to determine the temperature dependence of the magnetic structure in all four systems. Single-crystal inelastic neutron scattering is employed to investigate the temperature dependence of the Haldane-gap excitations and low-energy spin waves in the x=1 compound Nd_2 Ba Ni O_5. The results of these experiments are discussed in the context of the ``Haldane chain in a staggered field'' model for R_2 Ba Ni O_5 systems, and quantitative agreement with theory is obtained.

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T. Yokoo, S. Raymond, A. Zheludev, S. Maslov, E. Ressouche, I. Zaliznyak, R. Erwin, M. Nakamura, J. Akimitsu. 1998-03-09. Magnetic ordering, spin waves, and Haldane gap excitations in (Nd_x Y_{1-x})_2 Ba Ni O_5 linear-chain mixed-spin antiferromagnets. https://doi.org/10.1103/physrevb.58.14424

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