LDA+DMFT study of magnetic transition and metallization in CoO under pressure

Abstract

The magnetic and spectral properties of the paramagnetic phase of CoO at ambient and high pressures have been calculated within the LDA+DMFT method combining local density approximation (LDA) with dynamical mean-field theory (DMFT). From our results CoO at ambient pressure is a charge transfer insulator in the high-spin t2g5eg2 configuration. The energy gap is continuously decreased, and finally a transition into metallic state occurs with the increase in pressure that is consistent with experimental behavior of electrical resistivity. Notably, the metal-insulator transition in CoO is found to be accompanied by the high-spin to low-spin (HS-LS) transition in agreement with XES data. The metal-insulator transition is orbital selective in the t2g states of cobalt only, whereas the eg states become metallic after the spin transition at higher pressures.