Photoemission evidence for a Mott-Hubbard metal-insulator transition in VO${}_2$

Abstract

The temperature ($T$) dependent metal-insulator transition (MIT) in VO${}_2$ is investigated using bulk sensitive hard x-ray ($\sim$ 8 keV) valence band, core level, and V 2$p-3d$ resonant photoemission spectroscopy (PES). The valence band and core level spectra are compared with full-multiplet cluster model calculations including a coherent screening channel. Across the MIT, V 3$d$ spectral weight transfer from the coherent ($d^1\underline{\text{C}}$ final) states at Fermi level to the incoherent ($d^0+d^1\underline{\text{L}}$ final) states, corresponding to the lower Hubbard band, lead to gap-formation. The spectral shape changes in V 1$s$ and V 2$p$ core levels as well as the valence band are nicely reproduced from a cluster model calculations, providing electronic structure parameters. Resonant-PES finds that the $d^1\underline{\text{L}}$ states resonate across the V 2$p-3d$ threshold in addition to the $d^0$ and $d^1\underline{\text{C}}$ states. The results support a Mott-Hubbard transition picture for the first order MIT in VO${}_2$.

6 pages, 3 figures. to be published in Phys. Rev. B

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• Effective band-structure in the insulating phase versus strong dynamical correlations in metallic VO2
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• Cooperative Effects of Strain and Electron Correlation in Epitaxial VO2 and NbO2
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• Nature of the photo-induced metallic state in monoclinic VO${}_2$
• Atomic multiplet and charge-transfer screening effects in 1$s$ and 2$p$ core-level X-ray photoelectron spectra of early 3$d$ transition-metal oxides
• Electronic properties across metal-insulator transition in β-pyrochlore-type CsW2O6 epitaxial films
• Occupation switching of $d$ orbitals probed via hyperfine interactions in vanadium dioxide
• Effective Band Structure of Correlated Materials - The Case of VO2
• The isotropic Compton profile difference across the phase transition of VO${}_2$
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