Hund's rule and orbital anisotropy in the two-band Hubbard model: a finite-temperature slave-spin approach

MEZIO, ALEJANDRO; MCKENZIE, ROSS H.

Julich

Workshop; Jülich Autumn School on Correlated Electrons 2018 "DMFT: From Infinite Dimensions to Real Materials"; 2018

Institute for Advanced Simulation, Forschungszentrum Julich

The interest in therole of orbital degeneracy, Hund ́s rule, and multiple bands in stronglycorrelated electron materials has increased in the last years due to the study of transition metaloxides, colossal magnetoresistance, and the new iron-based superconductors. Recently it wasshown that Hund ́s rule has a complex effect on correlations: it modifies the critical value ofthe correlation above which a Mott insulator is formed in a way that depends on the number of electrons per site and the orbital character [1]. Here, we use the Slave-Spins Mean-FieldTheory (SSMFT) [2] to study the temperature dependence of paramagnetic phasesof the two-band Hubbard-Kanamori model and compare the one-band results with the slave-bosonsmean-field method [3]. We pay particular attention to how the Hund ́s rule and bandwidthanisotropy affects the coherence temperature T coh that signal the crossover from a Fermi liquidto a regime without quasiparticles, i.e., a bad metallic state. By calculating the quasiparticle