The spin and orbital orderings in perovskite transition metal oxides
Abstract
The electronic structure calculations in the density functional theory were performed for perovskite transition metal oxides LaMO_3. The calculated stablest spin orderings are the same as the experimentally obtained ones. The orbital orderings are successfully obtained by the electronic structure calculations for LaVO3 and LaMnO_3. In LaVO3 the orbital ordering and insulating state are realized only by the generalized gradient approximation (GGA). The local spin density approximation (LSDA) cannot yield the orbital ordering and insulating state. We have found that the relation between spin and orbital orderings is simply explained by the hybridization between the neighboring two M d states. The hybridization between occupied and unoccupied states lower the energy of the occupied state by approximately t^2/Δ, where t is an effective transfer integral and Δ is an energy difference between the occupied and unoccupied states. We examine which spin ordering is stabilized in LaMO3 by the energy gain of the hybridization. The experimentally obtained spin orderings are successfully realized in this analysis except for LaTiO_3. In this analysis the orbital ordering is very important for LaVO3 and LaMnO_3. The ferromagnetic state is stabilized for LaMnO_3, if the orbital ordering is not assumed.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 1996
- Bibcode:
- 1996APS..MAR..M910S