Eur. Phys. J. D (2015) 69: 268
https://doi.org/10.1140/epjd/e2015-60328-8

Regular Article

Localized spin excitations in a disordered antiferromagnetic chain with biquadratic interactions

Department of Physics, Women’s Christian College, 629001 Nagercoil, India

^a e-mail: lathaisaac@yahoo.com

Received: 2 June 2015
Received in final form: 14 September 2015
Published online: 3 December 2015

Abstract

Dynamical theory of soliton excitation in one dimensional antiferromagnet (AFM) is studied by a revised Hamiltonian in which biquadratic interaction is taken into account in addition to the uniaxial anisotropy and exchange energy. By using Holstein-Primakoff transformation, the coherent state ansatz and the time-dependent variational principle, we obtain a set of two coupled nonlinear partial differential equations that governs the dynamics of the system. Sine-cosine function method is used to study the complete nonlinear soliton excitation and the effect of inhomogeneity in the system. The presence of inhomogeneity is found to cause a disorder in the AFM system. Finally, the evolution of Modulational Instability (MI) is analyzed in the presence of small perturbations.