Optical spectra of Y1-xCaxVO3: Change of electronic structures with hole doping in Mott-Hubbard insulators.

Abstract

In perovskitelike solid solutions ${\mathrm{Y}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Ca}}_{\mathit{x}}$${\mathrm{VO}}_{3}$, the insulator-metal transition has been observed around x=0.5, which can be interpreted as being caused by hole doping in a Mott-Hubbard insulator ${\mathrm{YVO}}_{3}$. Change of electronic structures has been investigated by measurements and analyses of optical spectra. New electronic states were observed to grow within the Mott-Hubbard gap upon hole doping and eventually compose the states near the Fermi level in the metallic phase. Doping-induced changes of electronic structures are argued in comparison with the case of cuprate superconductors.