A DFT$+$DMFT study of magnetic properties of FeO at high pressure.

FeO is an insulator with anti-ferromagnetic (AFM) spin ordering at ambient pressure. When external pressure is increased, the N\'{e}el temperature first increases at the pressure below 40 GPa. Experiments show the AFM ordering collapses at high pressures. Using the density functional theory plus dynamical mean-field theory (DFT$+$DMFT), we examined the nature of magnetic collapse of FeO and derived its magnetic phase diagram up to 180 Gpa. We found coexistence of high spin-low spin transition and paramagnetic-AFM transition, both driven by increased pressure. The high spin-low spin transition is result of partition and pairing of 3d electrons in iron. The local moment of iron atom after high spin-low spin transition is small but finite up to 180 GPa.