Ferromagnetism in multi--band Hubbard models: From weak to strong Coulomb repulsion
Condensed Matter
2009-02-28 v1
Abstract
We propose a new mechanism which can lead to ferromagnetism in Hubbard models containing triangles with different on-site energies. It is based on an effective Hamiltonian that we derive in the strong coupling limit. Considering a one-dimensional realization of the model, we show that in the quarter-filled, insulating case the ground-state is actually ferromagnetic in a very large parameter range going from Tasaki's flat-band limit to the strong coupling limit of the effective Hamiltonian. This result has been obtained using a variety of analytical and numerical techniques. Finally, the same results are shown to apply away from quarter-filling, in the metallic case.
Cite
@article{arxiv.cond-mat/9603042,
title = {Ferromagnetism in multi--band Hubbard models: From weak to strong Coulomb repulsion},
author = {Karlo Penc and Hiroyuki Shiba and Frédéric Mila and Takuya Tsukagoshi},
journal= {arXiv preprint arXiv:cond-mat/9603042},
year = {2009}
}
Comments
12 pages, revtex, 12 figures,needs epsf and multicol style files