Random bond XXZ chains with modulated couplings
Abstract
The magnetization behavior of q-periodic antiferromagnetic spin 1/2 Heisenberg chains under uniform magnetic fields is investigated in a background of disorder exchange distributions. By means of both real space decimation procedures and numerical diagonalizations in XX chains, it is found that for binary disorder the magnetization exhibits wide plateaux at values of 1+2(p-1)/q, where p is the disorder strength. In contrast, no spin gaps are observed in the presence of continuous exchange distributions. We also study the magnetic susceptibility at low magnetic fields. For odd q-modulations the susceptibility exhibits a universal singularity, whereas for q even it displays a non-universal power law behavior depending on the parameters of the distribution.
Cite
@article{arxiv.cond-mat/0007205,
title = {Random bond XXZ chains with modulated couplings},
author = {D. C. Cabra and A. De Martino and M. D. Grynberg and S. Peysson and P. Pujol},
journal= {arXiv preprint arXiv:cond-mat/0007205},
year = {2009}
}
Comments
4 pages, 3 figures. Final version to appear in PRL