Spin Dynamics and Quantum Fluctuations in Quasi-One-Dimensional Triangular Antiferromagnets : Magnetic Field Effects

概要

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Neutron scattering experiments have revealed that the excitation spectrum in quasi-one-dimensional ABX_3-type antiferromagnets, such as CsNiCl_3, differs appreciably from the prediction of the conventional linear-spin-wave theory even in the ordered phase. It was shown in a previous paper that the spectrum could be explained well by including two-magnon excitation processes in the spin-wave expansion. Here the theory is extended to study magnetic properties of CsNiCl_3 in a magnetic field. The magnetization curve is found to vary with the field nonlinearly with about a half of the classical value. The excitation spectrum is remarkably affected by nonlinear processes. In addition to the effects which are seen at zero field, a hybridization effect and two-magnon peaks in a certain polarization are found to be significant. The results are compared with available experiments and phenomenological theories previously proposed.
社団法人日本物理学会の論文
1994-09-15