We investigate the doped perovskite manganites by using some elementary strong-correlation models. We focus mainly on the electronic motion through double-exchange and include the spin and lattice fluctuations solely to lift any residual degeneracy. We consider the low-energy physics of the strong-coupling limit, incorporating the spatial structure of the orbitals carefully. Due to a mismatch between the point-symmetries of the orbitals and the lattice, we find a highly geometrically frustrated Hubbard-like model. When orbital superexchange is dominant, the system finds ordering very difficult, and when the charge-carrier motion is dominant, the styles of orbital order are expected to be fairly complicated. Unless the system exhibits Fermi-liquid behaviour, the strong correlations are suggested to be uncontrollable at present.
|Number of pages||23|
|Journal||Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences|
|Publication status||Published - 15 Jul 1998|