High-Field ESR in Low-Dimensional Spin Systems


High-Field ESR in Low-Dimensional Spin Systems

Zvyagin, S.

Quantum fluctuations in low-dimensional magnets give rise to a variety of exotic strongly correlated states, making those systems an extremely attractive ground for testing various theoretical concepts. In this presentation I will focus on high-field ESR studies of two spin-chain systems. The first system is copper pyrimidine dinitrate, a material containing S=1/2 antiferromagnetic chains with alternating g-tensor and the Dzyaloshinskii-Moriya interaction and exhibiting a field-induced spin gap. Signatures of three breather branches and a soliton excitation have been identified [1,2], which is in excellent agreement with predictions of the sine-Gordon quantum field theory. In addition, a field-induced crossover from the soliton-breather to the magnon state was observed in this material in higher magnetic field [3]. The second material is NiCl2-4SC(NH2)2 (DTN), a quantum spin-1 chain system with strong easy-pane anisotropy. Using high-field ESR data, a revised set of spin-Hamiltonian parameters has been obtained [4]. These values were 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 was obtained.

  • Invited lecture (Conferences)
    Fakultät für Physik und Geowissenschaften Universität Leipzig, 25.05.2010, Leipzig, Deutschland

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Publ.-Id: 14117