Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 16: Posters Correlated Electrons, Measuring Devices, Cryotechnique

TT 16.65: Poster

Samstag, 5. März 2005, 11:00–16:30, Poster TU C

Spin gap and charge order in weakly coupled quarter-filled ladders — •Bernhard Edegger^1,2, Hans Gerd Evertz², and Reinhard M. Noack³ — ¹Theoretische Physik, Universität des Saarlandes — ²Insitut für Theoretische Physik, Technische Universität Graz — ³Fachbereich Physik, Philipps Universität Marburg

We present DMRG (Density Matrix Renormalization Group) calculations in quarter-filled ladders with model parameters relevant for NaV₂O₅. The properties of the low temperature phase are well described by including the coupling of the electrons to static lattice distortions in the extended Hubbard model. Charge order, charge gap and the effective magnetic exchange constant are determined. In addition, we show that a spin gap is induced by super-anti-ferroelectric charge order in weakly coupled quarter-filled ladders.