Ferrimagnetism in the Hubbard, dimmer-connector frustrated chain

• 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
• 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.

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.