Effects of biquadratic exchange interaction on dynamic susceptibility in Heisenberg ferromagnet

Abstract

The Green function technique has been employed to study the dynamic susceptibility of a spin-1 system above the Curie temperature. Bilinear and biquadratic terms have been added in writing the Hamiltonian of the system. Higher order Green functions have been decoupled by RPA and Callen type decouplings. The dependence of spin wave energy, intensity and susceptibility on wavevector and biquadratic parameter have been studied. © 1983.