Orbital physics in transition-metal oxides from first-principles

Transition-metal oxides often possess charge, spin, and orbital degrees of freedom, and they are a platform for many functional materials. It is the interplay among those degrees of freedom which gives rise to the diverse properties, typically associated with the orbital physics. In this article, we will provide an overview of our first-principles studies on the orbital physics in transition-metal oxides, which include (1) orbital ordering in the layered manganite La0.5Sr1.5MnO4 due to an anisotropic crystal field, (2) orbital ordering in the ferromagnetic insulator Cs2AgF4, (3) spin–orbital state transition and varying electronic and magnetic properties in the cobaltate series La2−xSrxCoO4, and (4) spin–orbit coupling and Ising magnetism in Ca3Co2O6, Ca3CoMnO6, and Sr3NiIrO6. Apparently, orbital physics spans 3d–4d–5d transition-metal oxides.