The Orbital-Selected Mott Phase of the Nondegenerate Two-Orbital Hubbard Model

We use the dynamical mean-field theory to study the optical conductivity and orbital susceptibility of the nondegenerate two-orbital Hubbard model in the orbital-selective Mott phase. The optical conductivity of the wide band presents expectedly a nonzero Drude peak, while the localization character is observed for the optical conductivity of the narrow band. Particularly, a rapidly reverse shape in the orbital susceptibility emerges right at Fermi surface, implying the coexistence of the orbital ordering with the orbital-selected Mott phase. We also find that the orbital-selected Mott transition can be suppressed by the negative crystal field splitting. Applying the present findings to compound Ca$_{2-x}$Sr$_{x}$RuO$_{4}$, we demonstrate that the orbital-selected Mott phase can not survive in wide doping region from $x$=0.2 to 2.0.