We investigated the electronic structures of the perovskite-type $4d$ transition-metal oxides $\mathrm{Sr}M{\mathrm{O}}_3$ $(M=\mathrm{Zr},$ Mo, Ru, and Rh) using their optical conductivity spectra $\sigma \left(\omega \right).\mathrm{}$ The interband transitions in $\sigma \left(\omega \right)$ are assigned, and some important electronic structure parameters, such as charge-transfer energy ${\Delta }_{\mathrm{pd}},$ and crystal-field splitting $10Dq,$ are estimated. It is observed that ${\Delta }_{\mathrm{pd}}$ and $10Dq$ decrease systematically with increasing the atomic number of the $4d$ transition metal. Compared with the case of $3d$ oxides, the magnitudes of ${\Delta }_{\mathrm{pd}}$ and $10Dq$ are larger. These behaviors can be explained by the more extended nature of the orbitals in the $4d$ oxides.

• Received 12 June 2002

DOI:https://doi.org/10.1103/PhysRevB.67.113101