Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 31: Correlated Electrons: Metal Insulator Transition - Part 2

TT 31.6: Vortrag

Donnerstag, 30. März 2006, 15:15–15:30, HSZ 301

Orbital fluctuations and Mott gap in LaVO₃ and YVO₃ — •E. Pavarini¹, M. Raychaudhury², and O.K. Andersen² — ¹IFF-Forschungzentrum Juelich, D-52425 Germany — ²MPI-FKF, Heisenbergstrasse 1, D-70569 Stuttgart

The Mott insulators LaVO₃ and YVO₃ have attracted a lot of attention because of their anomalous magnetic and electronic properties, which are ascribed to the interplay bewteen orbital (t_2g) degrees of freedom, lattice and Coulomb repulsion. Here, by using the Nth-order Muffin Tin Orbital (NMTO)-based downfolding procedure, we construct a low energy Hubbard Hamiltonian for the partially filled t_2g bands; we than solve this Hamiltonian by means of LDA+DMFT, and obtain the full self-energy matrix in orbital space; we have already applied successfully this approacht to the series of 3d¹ perovskites [1]. We will show that, in the case of LaVO₃ and YVO₃, orbital fluctuations are strong (more for LaVO₃ than for YVO₃) in the high temperature paramagnetic phase, and that they play an important role also in the low temperature magnetic phases. The interplay between filling, Coulomb repulsion, crystal field splitting and band widths is discussed, and their role in determining the size of the Mott gap in LaVO₃ and YVO₃ clarified.

[1] E. Pavarini, S. Biermann, A. Poteryaev, A.I. Lichtenstein, A. Georges, and OK Andersen, PRL 92 176403 (2004).