We study the effects of the degeneracy of the (Formula presented) orbitals in perovskite transition-metal oxides in the limit of strong repulsive electron-electron interaction. The isospin field is introduced to describe the orbital degrees of freedom and is represented by the boson with a constraint. The dispersion of this boson is flat along (Formula presented): lattice constant) and the other two equivalent directions. This enables the orbital disordered phase down to low temperatures. Some of the anomalous experiments in the low-temperature ferromagnetic phase of La(Formula presented)Sr(Formula presented)MnO(Formula presented) are interpreted in terms of this orbital liquid picture. The coupling between the orbital degrees of freedom and the Jahn-Teller lattice distortion and its implications to the optical conductivity are also discussed.
|Number of pages||7|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 1997|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics