Electronic structure, magnetic properties, and mechanism of the insulator-metal transition in LaCoO3 taking into account strong electron correlations

The electronic structure of LaCoO3 at finite temperatures is calculated using the LDA+GTB method taking into account strong electron correlations and possible spin crossover upon an increase in temperature. Gap states revealed in the energy spectrum of LaCoO3 reduce the dielectric gap width upon heating; this allowed us to describe the insulator-metal transition observed in this compound at T = 500-600 K. The temperature dependence of the magnetic susceptibility with a peak at T a parts per thousand 100 K is explained by the Curie contribution from thermally excited energy levels of the Co3+ ion. At high temperatures, the Pauli contribution from a band electron is added and the total magnetization of LaCoO3 is considered as the sum M (tot) = M (loc) + M (band). The second term describes the band contribution appearing as a result of the insulator-metal transition and facilitating the emergence of a high-temperature anomaly in the magnetic susceptibility of LaCoO3.