Orbital ordering in Mott-insulators La2O3Fe2Se2 and La2O3Co2Se2

The electronic structure and magnetic properties of new layered oxyselenide compounds La2O3Fe2Se2 and La2O3Co2Se2 are studied by first-principles calculations. Our results indicate that both compounds are Mott-insulators with orbital ordering. The ground states of both compounds are the checkerboard antiferromagnetic states, which are different from the iron pnictide superconductors, although their structures are similar to those of the Fe–As-based superconductors.