2019/07/30 by Majid, S. S., Gautam, K., Ahad, A. +4
#FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el)
paper · doi:10.48550/arxiv.1907.12746
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\itdx2-y2 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 π∗ and the σ∗ states (which are O 2\itp hybridized V 3\itd egπ and egσ states) in the conduction band. Experimentally obtained values of the correlation parameter (Udd ∼ 5.1 eV, intra-atomic V 3\itd correlations) and crystal field splitting (10 Dq ∼ 2.5 eV) values are used to simulate the V \itL2,3 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.