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 intra-orbital 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 band insulating state and a ferromagnetic metal.
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Rüegg, A., Indergand, M., Pilgram, S. et al. Slave-boson mean-field theory of the Mott transition in the two-band Hubbard model. Eur. Phys. J. B 48, 55–64 (2005). https://doi.org/10.1140/epjb/e2005-00382-1
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DOI: https://doi.org/10.1140/epjb/e2005-00382-1