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تسجيل مستخدم جديدMott-Hubbard insulator-metal transition in the VO2 thin film: A combined XAS and resonant PES study
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S.S. Majid
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We have analyzed spectral weight changes in the conduction and the valence band across insulator to metal transition (IMT) in the VO2 thin film using X-ray absorption spectroscopy (XAS) and resonant photoemission spectroscopy (PES). Through temperature dependent XAS and resonant PES measurements we unveil that spectral changes in the d$_{|}$ states (V 3$it{d_{x^2-y^2}}$ orbitals) are directly associated with temperature dependent electrical conductivity. Due to presence of the strong electron-electron correlations among the d$_{|}$ states, across IMT, these states are found to exhibit significant intensity variation compared to insignificant changes in the $pi^{ast}$ and the $sigma^{ast}$ states (which are O 2$it{p}$ hybridized V 3$it{d}$ $e_g^{pi}$ and $e_g^{sigma}$ states) in the conduction band. Experimentally obtained values of the correlation parameter (U$_{dd}$ $sim$ 5.1 eV, intra-atomic V 3$it{d}$ correlations) and crystal field splitting (10 Dq $sim$ 2.5 eV) values are used to simulate the V $it{L_{2,3}}$ edge XAS spectra and an agreement between simulated and experimental spectra also manifests strong correlations. These results unravel that the IMT observed in the VO2 thin film is the Mott-Hubbard insulator-metal transition.
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