Inter-site Coulomb interaction and Heisenberg exchange
Abstract
Based on exact diagonalization results for small clusters we discuss the effect of inter-site Coulomb repulsion in Mott-Hubbard or charge transfer insulators. Whereas the exchange constant J for direct exchange is substantially enhanced by inter-site Coulomb interaction, that for superexchange is suppressed. The enhancement of J in the single-band models holds up to the critical value for the charge density wave (CDW) instability, thus opening the way for large values of J. Single-band Hubbard models with sufficiently strong inter-site repulsion to be near a CDW instability thus may provide `physical' realizations of t-J like models with the `unphysical' parameter ratio J/t=1.
Keywords
Cite
@article{arxiv.cond-mat/9605117,
title = {Inter-site Coulomb interaction and Heisenberg exchange},
author = {R. Eder and J. van den Brink and G. A. Sawatzky},
journal= {arXiv preprint arXiv:cond-mat/9605117},
year = {2009}
}
Comments
Revtex file, 4 PRB pages, with 5 embedded ps-files. To appear in PRB, rapid communications. Hardcopies of figures or the entire manuscript may also be obtained by e-mail request to: [email protected]