Exact Ground States for Quasi 1D Systems with Hubbard Interaction

Authors E. Kovács1, Zs. Gulácsi2

1 University of Miskolc, Egyetemváros, Department of Physics, 3515 Miskolc, Hungary

2 University of Debrecen, Department of Theoretical Physics, Bemtér 18/b, 4026 Debrecen, Hungary

Е-mail fizendre@uni-miskolc.hu
Issue Volume 4, Year 2012, Number 1
Dates Received 26 September 2011; revised manuscript received 23 February 2012; published online 14 March 2012
Citation E. Kovács, Zs. Gulácsi, J. Nano-Electron. Phys. 4 No 1, 01004 (2012)
PACS Number(s) 8.65.– k, 75.10.Jm
Keywords Strongly interacting systems, Hubbard model, Nanowires (9) , Ferromagnetism (7) , Exact solutions, Chain structures, Diamond chains.
Annotation Using a positive semidefinite operator technique we deduced exact ground states for a modified diamond chain described by a non-integrable Hubbard model with on-site repulsion. Our results are valid for arbitrary length of the chain and strength of the Hubbard interaction. For the analyzed parameter space region of the quasi 1D chain structure we found that two flat bands are present in the bare band structure of the system, both for zero and for a fixed value of magnetic field. We obtained ground states of nonmagnetic and ferromagnetic insulator type and studied their physical properties.

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