Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 26: Metal-Insulator Transition
TT 26.9: Vortrag
Donnerstag, 29. März 2007, 16:15–16:30, H19
Orbital-ordering and phase transitions in the Mott insulators LaVO3 and YVO3 — •Eva Pavarini1, Molly Raychaudhury2, and Ole Andersen3 — 1Institut fuer Festkoerperforschung, Forschungzentrum Juelich, D-52425 Juelich, Germany — 2S.N. Bose National Centre for Basic Sciences, Kolkata, India — 3Max-Planck-Institut fuer Festkoerperforschung, Stuttgart, Germany
We calculate the electronic structure of the Mott insulating 3d2 perovskites LaVO3 and YVO3. Using the first-principles NMTO downfolding method we construct a low energy Hubbard Hamiltonian for the 3d t2g bands; we solve this model by using dynamical mean-field theory. The calculated Hubbard bands and Mott gaps are in very good agreement with experimental spectroscopy data. We show that, while in YVO3 orbital fluctuations are already suppressed at room temperature, in LaVO3 this happens only in the low temperature monoclinic phase. In the low-temperature orbitally-ordered phases both the Jahn-Teller deformations of the VO6 and the covalent interaction between the empty La (Y) d orbitals and the occupied V t2g orbital concur to determine the type of orbital-ordering.