Bandwidth control in a perovskite-type ${3d}^1$-correlated metal ${\mathrm{Ca}}_{1-x}{\mathrm{Sr}}_x{\mathrm{VO}}_3.$ II. Optical spectroscopy

Optical conductivity spectra of single crystals of the perovskite-type ${3d}^1$ metallic alloy system ${\mathrm{Ca}}_{1-x}{\mathrm{Sr}}_x{\mathrm{VO}}_3$ have been studied to elucidate how the electronic behavior depends on the strength of the electron correlation without changing the nominal number of electrons. The reflectivity measurements were made at room temperature between 0.05 eV and 40 eV. The effective mass deduced by the analysis of the Drude-like contribution to the optical conductivity and the plasma frequency do not show critical enhancement, even though the system is close to the Mott transition. Besides the Drude-like contribution, two anomalous features were observed in the optical conductivity spectra of the intraband transition within the $3d$ band. These features can be assigned to transitions involving the incoherent and coherent bands near the Fermi level. The large spectral weight redistribution in this system, however, does not involve a large mass enhancement.