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Slave-boson theory of the Mott transition in the two-band Hubbard model

A. Rüegg·M. Indergand·S. Pilgram·M. Sigrist
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Abstract

We apply the slave-boson approach of Kotliar and Ruckenstein to the two-band Hubbard model with an Ising like Hund's rule coupling and bands of different widths. On the mean-field level of this approach we investigate the Mott transition and observe both separate and joint transitions of the two bands depending on the choice of the inter- and intraorbital Coulomb interaction parameters. The mean-field calculations allow for a simple physical interpretation and can confirm several aspects of previous work. Beside the case of two individually half-filled bands we also examine what happens if the original metallic bands possess fractional filling either due to finite doping or due to a crystal field which relatively shifts the atomic energy levels of the two orbitals. For appropriate values of the interaction and of the crystal field we can observe a a band insulating state and a ferromagnetic metal.

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A. Rüegg, M. Indergand, S. Pilgram, M. Sigrist. 2005-08-29. Slave-boson theory of the Mott transition in the two-band Hubbard model. https://doi.org/10.1140/epjb%2Fe2005-00382-1

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