Optical spectroscopy of bulk single crystals of VOx and TiOx

Abstract

We successfully grew bulk single crystals of ${\mathrm{VO}}_{x}$ and ${\mathrm{TiO}}_{x}$ with a sodium-chloride structure by the floating-zone method, and we performed optical reflectivity measurement and pump-probe spectroscopy to clarify the electronic structure of these series of compounds and their $x$ dependence. We found that optical spectra can be discussed on the basis of the Mott-Hubbard model, although a disorder arising from the deficiencies of Vi or Ti and O plays an important role in the electronic structure as well as their $x$ dependence.