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Haldane-gap excitations in the low-H_c 1-dimensional quantum antiferromagnet NDMAP

A. Zheludev·Y. Chen·C. L. Broholm·Z. Honda·K. Katsumata
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Abstract

Inelastic neutron scattering on deuterated single-crystal samples is used to study Haldane-gap excitations in the new S=1 one-dimensional quantum antiferromagnet NDMAP, that was recently recognized as an ideal model system for high-field studies. The Haldane gap energies $Δ_x=0.42$ meV, $Δ_y=0.52$ meV and $Δ_z=1.86$ meV, for excitations polarized along the a, b, and c crystallographic axes, respectively, are directly measured. The dispersion perpendicular to the chain axis c is studied, and extremely weak inter-chain coupling constants $J_y=1.8\cdot 10^{-3}$ meV and $J_x=3.5\cdot 10^{-4}$ meV, along the a and b axes, respectively, are determined. The results are discussed in the context of future experiments in high magnetic fields.

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A. Zheludev, Y. Chen, C. L. Broholm, Z. Honda, K. Katsumata. 2000-03-13. Haldane-gap excitations in the low-H_c 1-dimensional quantum antiferromagnet NDMAP. https://doi.org/10.1103/physrevb.63.104410

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