Fermionic versus bosonic descriptions of one-dimensional spin-gapped antiferromagnets

Shoji Yamamoto; Kei-ichi Funase

doi:10.1063/1.2008134

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Fermionic versus bosonic descriptions of one-dimensional spin-gapped antiferromagnets

Shoji Yamamoto·Kei-ichi Funase

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Abstract

In terms of spinless fermions and spin waves, we describe magnetic properties of a spin-1/2 ferromagnetic-antiferromagnetic bond-alternating chain which behaves as a Haldane-gap antiferromagnet. On one hand, we employ the Jordan-Wigner transformation and treat the fermionic Hamiltonian within the Hartree-Fock approximation. On the other hand, we employ the Holstein-Primakoff transformation and modify the conventional spin-wave theory so as to restore the sublattice symmetry. We calculate the excitation gap, the specific heat, the magnetic susceptibility, magnetization curves, and the nuclear spin-lattice relaxation rate with varying bond alternation. These schemes are further applied to a bond-alternating tetramerized chain which behaves as a ferrimagnet. The fermionic language is particularly stressed as a useful tool to investigate one-dimensional spin-gapped antiferromagnets, while the bosonic one works better for ferrimagnets.

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Shoji Yamamoto, Kei-ichi Funase. 2005-12-24. Fermionic versus bosonic descriptions of one-dimensional spin-gapped antiferromagnets. https://doi.org/10.1063/1.2008134

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