SOLITARY EXCITATIONS IN THE ANTIFERROMAGNET KCUF3

Employing the Holstein-Primakoff transformation, first the spin-Hamilt onian is transformed into a boson Hamiltonian. Then, using a coherent state ansatz, a time-dependent variational principle, and the continuu m approximation, two nonlinear coupled equations are obtained. Finally , these equations of motion, which describe the dynamics of the system , are reduced to one nonlinear Schrodinger equation with localized env elope soliton solutions. Introducing the inverse scattering transforma tion, single-, two-, and N-soliton solutions are obtained and the soli tary excitations in the antiferromagnet KCuF3 are investigated.