Electron correlation and Jahn-Teller interaction in manganese oxides

The interplay between the electron repulsion U and the Jahn-Teller electron-phonon interaction E-LR is studied with a large-d model for the ferromagnetic state of the manganese oxides. These two interactions collaborate to induce local isospin (orbital) moments and to reduce the bandwidth B. The retardation effect of the Jahn-Teller phonon with frequency Omega is especially important in reducing B, and a strong Omega dependence occurs even when the Coulomb interaction is dominant (U much greater than E-LR), as long as E-LR>Omega. The phonon spectrum consists of two components: a temperature-independent sharp peak at omega=Omega=Omega[(U+4E(LR))/U](1/2) and one corresponding to the Kondo peak. A comparison of these results with experiments suggest that Omega<E-LR<U in the metallic manganese oxides.