Electronic structure calculations for layered LaSrMnO4 and Ca2RuO4

The electronic structures and magnetic properties of layered perovskite LaSrMnO4 and Ca2RUO4 have been determined using the full-potential linearized augmented-plane-wave method within the local spin-density approximation (LSDA) and the LDA + U approach (LDA standing for local density approximation). The results of LSDA and LDA + U total-energy calculations show that the antiferromagnetic state of these materials is stable compared with the ferromagnetic and paramagnetic states. The LDA + U calculation results show that Jahn-Teller distortion of Mn-O and Ru-O octahedra produces an energy gap, and 3z(2) - r(2) and xy orbital ordering for LaSrMnO4 and Ca2RuO4, respectively. However, the LSDA calculation is not sufficient for describing the orbital ordering and fails to produce the band gap. The Jahn-Teller distortion stabilizes a two-dimensional planar antiferromagnetic state.