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TT: Fachverband Tiefe Temperaturen

TT 12: Correlated Electrons: Spin Systems and Itinerant Magnets 2

TT 12.1: Vortrag

Montag, 23. März 2009, 14:00–14:15, HSZ 304

Systematic derivation of generalized t-J models from Hubbard models away from half-filling — •Simone Hamerla¹ and Götz S. Uhrig^1,2 — ¹Technische Universität Dortmund, Lehrstuhl für Theoretische Physik I, 44221 Dortmund, Germany — ²School of Physics, University of New South Wales, Kensington 2052, Sydney NSW, Australia

Starting from a fermionic Hubbard model a generalized t-J model is constructed by eliminating charge fluctuations which change the number of double occupancies. The charge fluctuations are eliminated by a systematic change of basis performed by self-similar continuous unitary transformations [1]. The proliferating terms are truncated according to their spatial extension. The derivation of a generalized t-J model is possible as long as the system is dominated by the local repulsion. In the present work, we focus on the Hubbard model on the linear chain and on the square lattice. There are two main goals: one is to test different choices of the infinitesimal generator, the other is to elucidate the influence of doping.

[1] A. Reischl, E. Müller-Hartmann, G. S. Uhrig, Phys. Rev. B 70, 245124