Two-orbital Systems with Crystal Field Splitting and Interorbital Hopping

Abstract

The nondegenerate two-orbital Hubbard model is studied within the dynamic mean-field theory to reveal the influence of two important factors, i.e. crystal field splitting and interorbital hopping, on orbital selective Mott transition (OSMT) and realistic compound Ca${}_{2-x}$Sr${}_x$RuO${}_4$. A distinctive feature of the optical conductivity of the two nondegenerate bands is found in OSMT phase, where the metallic character of the wide band is indicated by a nonzero Drude peak, while the insulating narrow band has its Drude peak drop to zero in the mean time. We also find that the OSMT regime expands profoundly with the increase of interorbital hopping integrals. On the contrary, it is shown that large and negative level splitting of the two orbitals diminishes the OSMT regime completely. Applying the present findings to compound Ca${}_{2-x}$Sr${}_x$RuO${}_4$, we demonstrate that in the doping region from $x=0.2$ to 2.0, the negative level splitting is unfavorable to the OSMT phase.

7 pages with 5 figures

References in corpus (9)

• The numerical renormalization group method for quantum impurity systems
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• High-spin to low-spin and orbital polarization transitions in multiorbital Mott systems
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• Orbital-selective Mott-Hubbard transition in the two-band Hubbard model
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• Hybridisation in two-band Hubbard models with different bandwidths