Ferrimagnetism in the Hubbard, dimmer-connector frustrated chain

We study the AB2 "dimmer-connector" chain within a generalized Hubbard model, which contains site-dependent parameters, and different chemical potentials for A and B sites. Considering one electron per atom, we carry out exact calculations for finite clusters, and derive some asymptotic re...

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Published in:Condensed Matter Physics
Date:2010
Main Authors: Rössler, J., Mainemer, D.
Format: Article
Language:English
Published: Інститут фізики конденсованих систем НАН України 2010
Online Access:https://nasplib.isofts.kiev.ua/handle/123456789/32048
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Journal Title:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Cite this:Ferrimagnetism in the Hubbard, dimmer-connector frustrated chain / J. Rössler, D. Mainemer // Condensed Matter Physics. — 2010. — Т. 13, № 1. — С. 13704: 1-8. — Бібліогр.: 15 назв. — англ.

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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Summary:We study the AB2 "dimmer-connector" chain within a generalized Hubbard model, which contains site-dependent parameters, and different chemical potentials for A and B sites. Considering one electron per atom, we carry out exact calculations for finite clusters, and derive some asymptotic results, valid for macroscopic chains. We take a non-vanishing intra-dimmer electron hopping, thus departing from the condition of a bipartite lattice. In spite of that, the system persists ferrimagnetic in some region of the parameter space, thus generalizing a theorem of Lieb for bipartite lattices. A somewhat surprising result is that the ferrimagnetic phase is possible, even for a very large chemical potential jump between A and B sites. In another respect, we show that a previously reported macroscopic (2N) degenerancy of the AB2 Heisenberg chain ground state (GS) is fully removed on going to the (more fundamental) Hubbard model, yielding a non-magnetic GS.
ISSN:1607-324X