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Strictly localised triplet dimers on one- and two-dimensional lattices

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posted on 31.01.2013, 09:30 authored by Steven Jackson, John SamsonJohn Samson
Electrons may form inter-site pairs (dimers) by a number of mechanisms. For example, long-range (Fröhlich) electron-phonon interactions and strong on-site Hubbard U allow formation of small light bipolarons in some lattices. We identify circumstances under which triplet dimers are strictly localised by interference in certain one- and two-dimensional lattices. We assume a U-V Hamiltonian with nearest- and next-nearest-neighbour hopping integrals t and t', large positive U and attractive nearest- and next-nearest-neighbour interactions V and V'. In the square ladder and some two-dimensional bilayers, if the dimer Hilbert space is restricted to nearest- and next-nearest-neighbour dimers, triplet dimers become strictly localised for certain values of these parameters. For example, in a square ladder with t' = t and V' = V, all triplet bands become flat due to exact cancellation of hopping paths. We identify the localised eigenstates for all flat bands in each lattice. We show that many of the flat bands persist for arbitrary t/t' so long as other restrictions still apply.

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  • Science

Department

  • Physics

Citation

JACKSON, S. and SAMSON, J.H., 2011. Strictly localised triplet dimers on one- and two-dimensional lattices. Journal of Physics: Conference Series, 286 (1), 012051.

Publisher

IOP Publishing (© The authors)

Version

VoR (Version of Record)

Publication date

2011

Notes

Published under licence in Journal of Physics: Conference Series, by IOP Publishing Ltd. This article was presented at Condensed Matter and Materials Physics (CMMP10), 14-16 December 2010, Warwick University.

ISSN

1742-6588

eISSN

1742-6596

Language

en

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