Fermionic versus bosonic descriptions of one-dimensional spin-gapped antiferromagnets
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.
Keywords
Cite
@article{arxiv.cond-mat/0512631,
title = {Fermionic versus bosonic descriptions of one-dimensional spin-gapped antiferromagnets},
author = {Shoji Yamamoto and Kei-ichi Funase},
journal= {arXiv preprint arXiv:cond-mat/0512631},
year = {2009}
}
Comments
10 pages, 5 figures