Condensed Matter Physics Seminar

Hybrid Mott Band Metal Insulator Transitions

Professor Ansgar Liebsch
Forschungszentrum Juelich, Germany
Monday, April 16, 2007
Higgins 235, 3pm

The Mott transition in transition metal oxides consisting of partially filled t2g bands, such as Ca2RuO4, LaTiO3 and V2O3, is studied using a recent extension of exact diagonalization dynamical mean field theory to multi-band materials [1,2]. In agreement with previous QMC studies of LaTiO3 [3] and V2O3 [4], it is shown that the crystal filed splitting between t2g subbands is greatly enhanced by local Coulomb interactions, giving rise to a filling or emptying of one subset of t2g bands and a Mott transition in the remaining half-filled subset. Accordingly, the excitation gap involves transitions between the filled t2g bands and the upper Hubbard band of the half-filled subset, or the lower Hubbard band of the half-filled subset and the remaining emtpy t2g bands. The Mott transition in these materials may therefore be described as a hybrid Mott band metal insulator transition.

[1] A. Perroni, H. Ishida, A. Liebsch, PRB (2007)
[2] H. Ishida, A. Liebsch, cond-mat/0812539
[3] E. Pavarini et al, PRL (2004)
[4] H. Keller et al, PRB (2004); A. Poteryaev et al, cond-mat/0701