title: Magnetic excitations in the spin-1 anisotropic Heisenberg antiferromagnetic chain system NiCl(2)-4SC(NH(2))(2).
abstract: NiCl(2)-4SC(NH(2))(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)10.1103/PhysRevLett.96.077204], a revised set of spin-Hamiltonian parameters is obtained. Our results yield D=8.9 K, J(c) = 2.2 K, and J(a,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.
authors.affiliation: Dresden High Magnetic Field Laboratory (HLD), Forschungszentrum Dresden-Rossendorf, 01314 Dresden, Germany.
authors.forename: S A
authors.initials: SA
authors.lastname: Zvyagin
authors.forename: J
authors.initials: J
authors.lastname: Wosnitza
authors.forename: C D
authors.initials: CD
authors.lastname: Batista
authors.forename: M
authors.initials: M
authors.lastname: Tsukamoto
authors.forename: N
authors.initials: N
authors.lastname: Kawashima
authors.forename: J
authors.initials: J
authors.lastname: Krzystek
authors.forename: V S
authors.initials: VS
authors.lastname: Zapf
authors.forename: M
authors.initials: M
authors.lastname: Jaime
authors.forename: N F
authors.initials: NF
authors.lastname: Oliveira
authors.forename: A
authors.initials: A
authors.lastname: Paduan-Filho