Dynamical correlations across the spin-state transition inLaCoO3

Abstract

The electronic properties of $\mathrm{La}\mathrm{Co}{\mathrm{O}}_{3}$ across the spin-state transition are studied using the $\mathrm{LDA}+\mathrm{DMFT}$ method. Combining the local density approximation band structure of the $\mathrm{Co}\phantom{\rule{0.2em}{0ex}}3d$ orbitals in the low-spin state with multiorbital dynamical mean field theory for $U=5\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$, we investigate the evolution of the single-particle spectra at different spin states. We show that small differences in the orbital occupation can induce a smooth spin-state crossover due to large dynamical renormalizations of the energy splitting between the ${t}_{2g}$ and ${e}_{g}$ manifolds. We find large changes in the one-particle spectra that are unique fingerprints of each of the possible spin states. The key signature of the intermediate- and high-spin states is the presence of Hubbard satellites in the ${t}_{2g}$ spectral density. Further, our results for the paramagnetic metallic phase shows Kondo-like resonance in the ${t}_{2g}$ sector, indicating the role of multiorbital Kondo screening processes in the high-spin state. These results provide a theoretical basis for physics of room-temperature thermoelectric materials based on cobalt oxides.