Abstract
The key role of the orbital degree of freedom to understanding the magnetic properties of layered ruthenates is discussed based on the 3-orbital Hubbard model coupled to lattice distortions, using numerical and mean-field techniques. In the -type antiferromagnetic phase of , recent x-ray experiments reported 0.5 holes/site in the orbital, while and orbitals contain 1.5 holes. This unexpected hole distribution is explained by a novel orbital ordered (OO) state, stabilized by a combination of Coulombic and lattice effects. The phase diagram suggests the possibility of large magnetoresistance effects and a new ferromagnetic OO phase in ruthenates.
- Received 3 August 2001
DOI:https://doi.org/10.1103/PhysRevLett.88.017201
©2001 American Physical Society