Band dispersion near the Fermi level forVO2thin films grown onTiO2(001) substrates

Abstract

We have performed angle-resolved photoemission spectroscopy (ARPES) measurements of ${\text{VO}}_{2}$ using epitaxial thin films and observed the band dispersion near the Fermi level $({E}_{\text{F}})$ for this compound. The ${\text{VO}}_{2}$ thin films have been grown on ${\text{TiO}}_{2}$ (001) single-crystal substrates using pulsed laser deposition. The films exhibit a first-order metal-insulator transition (MIT) at 305 K. In the ARPES spectra of the metallic phase for the films, the $\text{O}\text{ }2p$ band shows highly dispersive features in the binding-energy range of 3--8 eV along the $\ensuremath{\Gamma}\ensuremath{-}Z$ direction. Also, the $\text{V}\text{ }3d$ state shows two dispersive bands around the $\ensuremath{\Gamma}$ point near ${E}_{\text{F}}$, indicative of two electron pockets centered at the $\ensuremath{\Gamma}$ point. Both electron pockets have an occupied bandwidth of about 0.4 eV. Assuming the parabolic energy bands around the $\ensuremath{\Gamma}$ point, the effective-mass ratios of the two electron pockets are estimated to be about 0.2 and 1. The present work indicates that the ARPES measurements using epitaxial thin films are promising for determining the band structure of ${\text{VO}}_{2}$ and thus would play a crucial role to elucidate the mechanism of the MIT in ${\text{VO}}_{2}$.