Magnetic Properties of Antiferromagnetic Heisenberg Linear Chain

概要

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By the Green's function method, where spin operators are transformed to fermion operators, an antiferromagnetic Heisenberg chain system has been investigated within the Hartree=Fock approximation. The static correlation <S^z_kS^z_<-k>> cannot be reduced to the Ornstein-Zernike form and has no singularity at k=π. The absorption function x^"_<zz>(k, ω) cannot be expressed by the δ-function-like spectrum even at 0°K, but rather by a narrow diffused one, which is due to the two-magnon process. The present dispersion relation has a gap at k=π for T=0°K. The second order phase transition, then, may not occur in the linear chain. The results obtained are discussed comparing with those in the X-Y model and experimental data on TMMC.
理論物理学刊行会の論文
1973-10-25