The temperature (T) -dependent metal-insulator transition (MIT) in VO2 is investigated using bulk sensitive hard-x-ray (∼8keV) valence-band, core-level, and V2p-3d resonant photoemission spectroscopies (PESs). The valence-band and core-level spectra are compared with full-multiplet cluster model calculations including a coherent screening channel. Across the MIT, V3d spectral weight transfer from the coherent (3 d1 C final) states at Fermi level to the incoherent (3 d0 +3 d1 L final) states, corresponding to the lower Hubbard band, leads to gap formation. The spectral shape changes in V1s and V2p core levels as well as the valence band are nicely reproduced from cluster model calculations, providing electronic structure parameters. Resonant PES finds that the 3 d1 L states resonate across the V2p-3d threshold in addition to the 3 d0 and 3 d1 C states. The results support a Mott-Hubbard transition picture for the first-order MIT in VO2.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Aug 18 2008|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics