Microscopic theory of dynamic spin susceptibility in charge ordered CMR systems

The spectral density function of neutron scattering is directly proportional to the imaginary part of the dynamic magnetic spin susceptibility. An attempt is made in the present communication to calculate the longitudinal spin susceptibility for the colossal magneto-resistive manganites to observe the resonance peaks at the magnetic and CDW interaction energies. The model Hamiltonian consists of s-d type exchange interaction between the spins of itinerant eg and core t2g electrons and Heisenberg type t2g core electron spin interactions. In addition, there exists a CDW interaction in the eg band due to charge disproportion in Mn3+ and Mn4+ ions. The magnetic susceptibility is evaluated by using equations of motion of Zubarev’s technique for a two particle Green’s function. The effect of CDW interaction on dynamic spin susceptibility is investigated.