Angle-resolved photoemission spectroscopy for VO_2 thin films grown on TiO_2 (0 0 1) substrates

摘要

We present the results of angle-resolved photoemission spectroscopy (ARPES) measurements of metallic VO_2 thin films. The VO_2 thin films have been grown on TiO_2 (0 0 1) 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 O 2p band shows highly dispersive feature in the binding energy range of 3-8 eV along the Γ-Z direction. The periodicity of the dispersive band is found to be 2.2?~(-1) which is almost identical with the periodicity expected from the c-axis length of the VO_2 thin films. The overall feature of the experimental band structure is similar to the band structure calculations, supporting that we have succeeded in observing the dispersive band of the O 2p state in the metallic VO_2 thin film. The present work indicates that the ARPES measurements using epitaxial thin films are promising for determining the band structure of VO_2.