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Coulomb Correlations Intertwined with Spin and Orbital Excitations in LaCoO3
K. Tomiyasu, J. Okamoto, H. Y. Huang, Z. Y. Chen, E. P. Sinaga, W. B. Wu, Y. Y. Chu, A. Singh, R.-P. Wang, F. M. F. de Groot, A. Chainani, S. Ishihara, C. T. Chen, and D. J. Huang
We carried out temperature-dependent (20–550 K) measurements of resonant inelastic x-ray scattering on LaCoO3 to investigate the evolution of its electronic structure across the spin-state crossover. In combination with charge-transfer multiplet calculations, we accurately quantified the renomalized crystal-field excitation energies and spin-state populations. We show that the screening of the effective on-site Coulomb interaction of 3d electrons is orbital selective and coupled to the spin-state crossover in LaCoO3 . The results establish that the gradual spin-state crossover is associated with a relative change of Coulomb energy versus bandwidth, leading to a Mott-type insulator-to-metal transition.