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arXiv · 0709.1779

Magnetic properties of the Haldane-gap material NENB

E. Cizmar·M. Ozerov·O. Ignatchik·T. P. Papageorgiou·J. Wosnitza·S. A. Zvyagin·J. Krzystek·Z. Zhou·C. P. Landee·B. R. Landry·M. M. Turnbull·J. L. Wikaira
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Abstract

Results of magnetization and high-field ESR studies of the new spin-1 Haldane-chain material [Ni(C2H8N2)2NO2](BF4) (NENB) are reported. A definite signature of the Haldane state in NENB was obtained. From the analysis of the frequency-field dependence of magnetic excitations in NENB, the spin-Hamiltonian parameters were calculated, yielding Delta = 17.4 K, g_parallel = 2.14, D = 7.5 K, and |E| = 0.7 K for the Haldane gap, g factor and the crystal-field anisotropy constants, respectively. The presence of fractional S = 1/2 chain-end states, revealed by ESR and magnetization measurements, is found to be responsible for spin-glass freezing effects. In addition, extra states in the excitation spectrum of NENB have been observed in the vicinity of the Haldane gap, which origin is discussed.

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E. Cizmar, M. Ozerov, O. Ignatchik, T. P. Papageorgiou, J. Wosnitza, S. A. Zvyagin, J. Krzystek, Z. Zhou, C. P. Landee, B. R. Landry, M. M. Turnbull, J. L. Wikaira. 2007-09-12. Magnetic properties of the Haldane-gap material NENB. https://doi.org/10.1088/1367-2630%2F10%2F3%2F033008

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