Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 30: Correlated Electrons: Spin Systems and Itinerant Magnets 2

TT 30.2: Vortrag

Donnerstag, 28. Februar 2008, 10:45–11:00, EB 202

Topological excitations of correlated spinless fermions: slave boson approach — •Sebastien Burdin and Mukul Laad — Max-Planck-Institut PKS, Nöthnitzer Strasse 38, 01187 Dresden, Germany

We study the general problem of spinless electrons on a periodic lattice, with a nearest neighbor exchange t and a nearest neighbor Coulomb repulsion V. Following the approach of the slave boson approximation, we introduce auxiliary bosons and fermions; a site with one electron corresponds to a site occupied by an auxiliary fermion, and an empty site is represented by a boson. The fermionic degrees of freedom are then formally integrated, providing an effective action for the bosonic field. This effective action is solved analytically in the specific case of a square lattice at half filling in the regime t≪ V. The ground state is a charge ordered insulator. We show analytically that in the continuum limit the low energy excitations are collective solitonic excitations. Our results confirm some results which have been previously obtained from numerical simulations [1]. They also provide a systematic analytical scheme which might allow us to describe fractional charge excitations of frustrated electronic systems [2].

[1] P.M.R. Brydon, J.X. Zhu, and A.R. Bishop, cond-mat/0509764

[2] P. Fulde, K. Penc, and N. Shannon, Ann. Phys. (Berlin) 11, 892 (2002)