Abstract
Electronic structure of the layered perovskite with a checkerboard charge order is studied, using the local-spin-density approximation plus Hubbard calculations including also the spin-orbit coupling and multiplet effect. Our results show that the ion is in a high spin state (HS, ) and low spin state (LS, ). Due to a small crystal field splitting, the spin-orbit interaction produces an orbital moment of and accounts for the observed easy in-plane magnetism. Moreover, we find that the intermediate spin state (IS, ) has a multiplet splitting of several tenths of eV and the lowest-lying one is still higher than the LS ground state by 120 meV, and that the HS state is more unstable by 310 meV. Either the IS or HS ions would give rise to a wrong magnetic order and anisotropy.
- Received 24 July 2009
DOI:https://doi.org/10.1103/PhysRevB.80.081105
©2009 American Physical Society