Magnetism of the Nearly One-Dimensional Helical Spin System

概要

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Magnetic properties of the nearly one-dimensional helical magnet VF_2 are studied by the two-time Green function method. The Neel temperature, T_N, sublattice magnetization, and susceptibility along the c axis, X_c, below T_N are calculated by using the Tyablikov, Callen, and modified Callen decouplings. The results for T_N are much lower than the molecular-field estimate and found to be fairly close to that ovserved. The measured temperature dependence of X_c is qualitatively consistent only with the Callen decoupling prediction. Then, by using this decoupling, various spin-correlation functions, magnon energies renormalized by a k-dependent factor, and X_c above T_N are calculated. The temperature dependence of the turn angle is also studied, and the ratio of the exchange constants between and within linear chains is found to be about 0.156. For comparison a similar but three-dimensional magnet MnO_2 is treated.
社団法人日本物理学会の論文
1974-09-15