Neutron scattering studies in the linear-chain haldane materials, NDMAZ and NDMAP

Yoshihiro Koike, Naoto Metoki, Yukio Morii, Tatsuo Kobayashi, Tomohiko Ishii, Masahiro Yamashita

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Neutron scattering experiments were carried out in order to investigate the field-induced antiferromagnetic long-range order and spin dynamics for the new Haldane compounds Ni(C5H14N2)2N3(ClO 4) (NDMAZ) and Ni(C5H14N2)2N3(PF 6) (NDMAP). We observed the energy gaps corresponding to the excited triplet, Δx = 1.61 meV, Δy = 1.76 meV, Δz = 3.2 meV for NDMAZ and Δx = 0.48 meV, Δy = 0.64 meV for NDMAP. The dispersion in NDMAZ was well explained by the theoretical curve with the intra-chain interaction J = 50 K. The field dependence of the gap energy below critical field (Hc), was observed for NDMAZ and NDMAP as applying the field perpendicular to the chain direction. The field dependence of the excitation levels in NDMAZ was well explained by the fermionic field-theory treatment of the one-dimensional Heisenberg antiferromagnetic Hamiltonian with these gap energies and g-value, 2.3. In NDMAP, we found that the excitation peaks at Q = (0 0 0.5) became unobservably weak above Hc. This result would indicate a level crossing between the ground and the excited level at Hc and the change of the ground state above Hc. No trace of the magnetic Bragg peak due to the field induced ordering could be observed in the present study with our non-deuterated single crystal sample.

Original languageEnglish
Pages (from-to)4034-4042
Number of pages9
Journaljournal of the physical society of japan
Volume69
Issue number12
DOIs
Publication statusPublished - Dec 2000
Externally publishedYes

Keywords

  • Haldane gap
  • MDMAP
  • NDMAZ
  • Neutron Scattering

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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