Coulomb correlations intertwined with spin and orbital excitations in LaCoO₃

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 renormalized 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.