NiCl2−4SC(NH2)2 (DTN) is a quantum S=1 chain system with strong easy-pane anisotropy and a new candidate for the Bose-Einstein condensation of the spin degrees of freedom. ESR studies of magnetic excitations in DTN in fields up to 25 T are presented. Based on analysis of the single-magnon excitation mode in the high-field spin-polarized phase and previous experimental results [Phys. Rev. Lett. 96, 077204 (2006)], a revised set of spin-Hamiltonian parameters is obtained. Our results yield D=8.9 K, Jc=2.2 K, and Ja,b=0.18 K for the anisotropy, intrachain, and interchain exchange interactions, respectively. These values are used to calculate the antiferromagnetic phase boundary, magnetization, and the frequency-field dependence of two-magnon bound-state excitations predicted by theory and observed in DTN for the first time. Excellent quantitative agreement with experimental data is obtained. (Abstract of Ref. [1])
(by Mitsuaki Tsukamoto)
Reference
[1] S. A. Zvyagin, J. Wosnitza, C. D. Batista, M. Tsukamoto, N. Kawashima, J. Krzystek, V. S. Zapf, M. Jaime, N. F. Oliveira, Jr., and A. Paduan-Filho: ” Magnetic Excitations in the Spin-1 Anisotropic Heisenberg Antiferromagnetic Chain System NiCl2-4SC(NH2)2″, Phys. Rev. Lett. 98, 047205 (2007).[2] Mitsuaki Tsukamoto, Cristian Batista and Naoki Kawashima: “Quantum Monte Carlo simulation for S=1 Heisenberg model with uniaxial anisotropy”, J. Magn. Magn. Mater. 310, 1360 (2007).
