Nonlinear nano-scale localized breather modes in a discrete weak ferromagnetic spin lattice

L. Kavitha, E. Parasuraman, D. Gopi, A. Prabhu and R.A. Vicencio
WORLD ACADEMY OF SCIENCE, ENGINEERING AND TECHNOLOGY 401 (2015)

ABSTRACT

We investigate the propagation dynamics of highly localized discrete breather modes in a weak ferromagnetic spin lattice with on-site easy axis anisotropy due to crystal field effect. We derive the discrete nonlinear equation of motion by employing boson mappings and p-representation. We explore the onset of modulational instability both analytically in the framework of linear stability analysis and numerically by means of molecular dynamics (MD) simulations, and a perfect agreement was demonstrated. It is also explored that how the antisymmetric nature of the canted ferromagnetic lattice supports highly localized discrete breather (DBs) modes as shown in the stability/instability windows. The energy exchange between low amplitude discrete breathers favours the growth of higher amplitude DBs, resulting eventually in the formation of few long-lived high amplitude DBs.

DOI: http://dx.doi.org/10.1016/j.jmmm.2015.10.021



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