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Dresden 2003 – scientific programme

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TT: Tiefe Temperaturen

TT 11: Postersitzung II (Metall-Isolator-Überg
änge, Phasenüberg
änge in Quantensystemen, Theorie: Systeme korrelierter Elektronen)

TT 11.18: Poster

Tuesday, March 25, 2003, 14:30–19:00, P2c, P2d

Nature of Band- to Mott-insulator Transitions in 1D — •Michael Sekania1, Arno P. Kampf1, George I. Japaridze2, Holger Fehske3, Philipp Brune1, and Gerhard Wellein41Institute fuer Physik, Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg, 86135 Augsburg, Germany — 2Institute fuer Physik, Ernst-Moritz-Arndt Universitaet Greifswald, 17487 Greifswald, Germany — 3Institute of Physics, Georgian Academy of Sciences, Tamarashvili str. 6, 380077, Tbilisi, Georgia — 4RRZE, Universitaet Erlangen, 91058 Erlangen, Germany

We investigate insulator-insulator phase transitions in the half-filled ionic Hubbard and the half-filled Holstein-Hubbard model using Lanczos exact diagonalization and DMRG techniques. In the ionic Hubbard model the interaction induced transition from a band- to a Mott-insulator is characterized by a vanishing optical excitation gap while charge and spin excitation gaps remain finite at the transition. In the adiabatic limit of the Holstein-Hubbard model two different band- to Mott-insulator transition scenarios are found: depending on the strength of the electron-phonon coupling and the Hubbard interaction the transition is either first order or evolves continuously across an intermidiate correlated insulator phase.

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