Abstract
We introduce a microscopic model which unravels the physical mechanisms responsible for the observed phase diagram of the perovskites. It reveals a nontrivial interplay between superexchange, the orbital-lattice coupling due to the -like rotations of the octahedra, and orthorhombic lattice distortions. We find that the lattice strain affects the onset of the magnetic and orbital order by partial suppression of orbital fluctuations. The present approach also provides a natural explanation of the observed reduction of magnon energies from to .
- Received 4 December 2007
DOI:https://doi.org/10.1103/PhysRevLett.100.167205
©2008 American Physical Society