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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/0612539 [3] E. Pavarini et al, PRL (2004) [4] H. Keller et al, PRB (2004); A. Poteryaev et al, cond-mat/0701 |
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