Excitation Spectrum of the Spin-1/2 Ferromagnetic-Antiferromagnetic Alternating Heisenberg Chain:

Abstract

The natural explanation of the excitation spectrum of the spin-1 antiferromagnetic Heisenberg chain is given from the viewpoint of the spin-1/2 ferromagnetic-antiferromagnetic alternating Heisenberg chain. The energy spectrum of the latter is calculated with fixed momentum $k$ by numerical diagonalization of finite size systems. It consists of a branch of propagating triplet pair (triplet wave) and the continuum of multiple triplet waves for weak ferromagnetic coupling. As the ferromagnetic coupling increases, the triplet wave branch is absorbed in the continuum for small $k$, reproducing the characteristics of the spin-1 antiferromagnetic Heisenberg chain.

12 Pages REVTEX, Postscript file for the figures included. SKPH-94-C001

References in corpus (4)

• Phase diagram of the S=1/2 quantum spin chain with bond alternation
• Solitonic excitations in the Haldane phase of a S=1 chain
• S(k) for Haldane Gap Antiferromagnets: Large-scale Numerical Results vs. Field Theory and Experiment
• Impurity-Bond Effect on the Spin-1 Antiferromagnetic Heisenberg Chain

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• Phase transitions and magnetization of the mixed-spin Ising-Heisenberg double sawtooth frustrated ladder
• Alternating Heisenberg Spin-1/2 Chains in a Transverse Magnetic Field
• Fermionic versus bosonic descriptions of one-dimensional spin-gapped antiferromagnets
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• Interacting Boson Theory of the Magnetization Process of the Spin-1/2 Ferromagnetic-Antiferromagnetic Alternating Heisenberg Chain
• Spin-dynamics of the low-dimensional magnet (CH3)2NH2CuCl3
• Effects of a space modulation on the behavior of a 1D alternating Heisenberg spin-1/2 model
• The specific heat and magnetic properties of a spin-1/2 ladder including butterfly-shaped unit blocks
• Electronic structure, magnetic properties and pairing tendencies of the copper-based honeycomb lattice Na${}_2$Cu${}_2$TeO${}_6$
• Studies on a frustrated Heisenberg spin chain with alternating ferromagnetic and antiferromagnetic exchanges
• Spin-1/2 Ising-Heisenberg Cairo pentagonal model in the presence of an external magnetic field: Effect of Landé g-factors
• Magnetic properties of the spin $S=1/2$ Heisenberg chain with hexamer modulation of exchange
• Haldane and Dimer phases in a frustrated spin chain: an exact groundstate and associated topological phase transition
• Zero-temperature study of a tetrameric spin-$1/2$ chain in a transverse magnetic field