Spin-orbit coupling and correlations in a 3-band model system In materials with sizable electron-electron correlation, such as perovskites with open d-shells, for example, the effective mass of the quasiparticles is enhanced. At some critical interaction strength, a metal insulator transition (Mott transition) takes place as the effective mass diverges. In multi-orbital systems, the high-spin state is favored following Hund’s rules of atomic physics. Therefore, Hund‘s coupling has a large impact on the mass renormalization. |