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MEZIO Alejandro

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Título:

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

Autor/es:

MEZIO, ALEJANDRO; MCKENZIE, ROSS H.

Lugar:

Beijing

Reunión:

Conferencia; 12th International Conference on Materials and Mechanisms of Superconductivity and High Temperature Superconductors (M2S-2018); 2018

Institución organizadora:

National Lab for Superconductivity, Institue of Physics, Chinese Academy of Sciences

Resumen:

The interest in the role of orbital degeneracy, Hund's rule, and multiple bands in strongly correlated electron materials has increased in the last years due to the study of transition metal oxides, colossal magnetoresistance, and the new iron-basedsuperconductors. Recently it was shown that Hund's rule has a complex effect on correlations: it modifies the critical value of the 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-Field Theory (SSMFT) [2] to study the temperature dependence of paramagnetic phases of the two-band Hubbard-Kanamori model and compare the one-band results with the slave-bosons mean-field method [3]. We pay particular attention to how the Hund's rule and bandwidth anisotropy affects the coherence temperature Tcoh that signal the crossover from a Fermi liquid to a regime without quasiparticles, i.e., a bad metallic state. By calculating the quasiparticle spectral weight Z of each band, we can identify the Tcoh as the temperature where they collapse. Near the Mott metal-insulator transition, we find this Tcoh to be much lower than the Fermi temperature of the uncorrelated Fermi gas and to follow the effect of the Hund's rule on the ground state. We also explore the consequence of band anisotropy and discuss the appearance of a different Tcoh for each band, or otherwise the emergence of a common energy scale for two different bands.[1] A. Georges, L. de'Medici, and J. Mravlje, AnnualReview of Condensed Matter Physics 4,137 (2013).[2] L. de'Medici and M. Capone, in The Iron Pnictide Superconductors,edited by F. Mancini and R. Citro, Springer Series in Solid-State Sciences(2017), Vol. 186, p. 115-185.[3] A. Mezio and R. H. McKenzie, Physical Review B 96, 035121 (2017)

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