Disorder and Impurities in Hubbard-Antiferromagnets
Abstract
We study the influence of disorder and randomly distributed impurities on the properties of correlated antiferromagnets. To this end the Hubbard model with (i) random potentials, (ii) random hopping elements, and (iii) randomly distributed values of interaction is treated using quantum Monte Carlo and dynamical mean-field theory. In cases (i) and (iii) weak disorder can lead to an enhancement of antiferromagnetic (AF) order: in case (i) by a disorder-induced delocalization, in case (iii) by binding of free carriers at the impurities. For strong disorder or large impurity concentration antiferromagnetism is eventually destroyed. Random hopping leaves the local moment stable but AF order is suppressed by local singlet formation. Random potentials induce impurity states within the charge gap until it eventually closes. Impurities with weak interaction values shift the Hubbard gap to a density off half-filling. In both cases an antiferromagnetic phase without charge gap is observed.
Keywords
Cite
@article{arxiv.cond-mat/9804188,
title = {Disorder and Impurities in Hubbard-Antiferromagnets},
author = {M. Ulmke and P. J. H. Denteneer and V. Janis and R. T. Scalettar and A. Singh and D. Vollhardt and G. T. Zimanyi},
journal= {arXiv preprint arXiv:cond-mat/9804188},
year = {2009}
}
Comments
16 pages, 9 figures, latex using vieweg.sty (enclosed); typos corrected, references updated; to appear in "Advances in Solid State Physics", Vol. 38