COMPOSITE POLARONS IN FERROMAGNETIC NARROW-BAND METALLIC MANGANESE OXIDES

Moving electrons accompanied by Jahn-Teller phonon and spin-wave cloud s may form composite polarons in ferromagnetic narrow-band manganites. The ground-state and finite-temperature properties of such composite polarons are studied in the present paper. By using a variational meth od, it is shown that the energy of the system at zero temperature decr eases with the formation of the composite polaron and the composite po laron behaves as a Jahn-Teller phononic polaron; the energy spectrum o f the composite polaron at finite temperatures is found to be strongly renormalized by the temperature and the magnetic field. It is suggest ed that the composite polaron contributes significantly to the transpo rt and the thermodynamic properties in ferromagnetic narrow-band metal lic manganese oxides.