Model study of physical properties of manganite system

The colossal magnetoresistive (CMR) materials: the doped manganites exhibit strong correlations among the charges, spins, orbitals and the lattice. In this communication we present a microscopic theoretical model for the system and study the temperature variation of its magnetic susceptibility. The model Hamiltonian envisages Jahn-Teller static lattice distortion in the eg band and treats the ferromagnetic interaction of the electrons in the core t2g levels within the mean-field approximation, while incorporating the possibility of hybridization between the two bands. The two particle electron Green's functions involved in the susceptibility are calculated by Zubarev's technique. Finally, the experimental results are discussed on the basis of the parameter dependence of the dynamic susceptibility of the system in the long wavelength limit and at finite temperature.