Study of dynamic spin susceptibility in Kondo lattice

The dynamic spin susceptibility χ(q,ω)χ(q,ω), which is related to the inelastic neutron scattering cross-section, gives important information about the low energy excitations of the systems. The spectral density distribution function (SDF) of the neutron scattering is directly proportional to the imaginary part of the χ(q,ω)χ(q,ω). Attempt is made in the present communication to calculate the longitudinal spin susceptibility for heavy fermion systems (HFS) to study resonance peaks at correlation temperature (TN)(TN) and Kondo temperature (TK)(TK). The model Hamiltonian consists of c–f electron exchange term and Heisenberg type inter-site spin–spin correlation in a mean-field approximation, besides the terms containing the conduction electron and f-electron contributions in presence of the hybridization between them in the Hamiltonian. The two particle Green functions are calculated using the equations of motion by method of Zubarev's technique. The microscopic model calculation shows two resonance peaks, one at Kondo excitation energy and another at correlation energy exhibiting the excellent interplay between them for different model parameters.