M Saravanan

Solitonic transport of energy?momentum in a deformed magnetic medium

The energy–momentum transport phenomenon between interacting spins in a deformed ferromagnetic medium is investigated theoretically. The spin dynamics of a one-dimensional (1D) classical continuum Heisenberg ferromagnetic spin system in the presence of varying exchange interactions is considered. The state of the 1D continuum spin system with varying exchange interactions is mapped onto a moving helical space curve in E3. The results are recast in conjunction with the evolution of energy and current densities of the deformed ferromagnetic medium, through a knowledge of the underlying geometry of this system. A set of soliton solutions for energy and current densities is constructed by employing the sine–cosine method coupled with symbolic computation. The evolution and propagation of solitonic energy–momentum transport under the influence of competing linear and nonlinear inhomogeneities have been analyzed briefly.

Soliton switching in an anisotropic Heisenberg ferromagnetic spin chain with octupole–dipole interaction

We study the nonlinear spin excitations in a one-dimensional anisotropic Heisenberg ferromagnetic spin chain with octupole–dipole interaction by a semi-classical approach using Glaubers coherent state method combined with the Holstein–Primakoff bosonic representation for the spin operator in the continuum limit. The associated dynamics are governed by a generalized higher-order nonlinear Schrodinger equation. We point out that the presence of a higher-order influence of octupole–dipole interaction in the ferromagnetic medium enhances the magnetization switching process in the nanoscale regime through the flipping of a soliton.

Propagation of an electromagnetic soliton in an anisotropic biquadratic ferromagnetic medium

Information storage technology based on anisotropic ferromagnets with sufficiently high magneto-optical effects has received much attention in recent years. Magneto-optical recording combines the merits of magnetic and optical techniques. We investigate the magneto-optical effects on a biquadratic ferromagnet and show that the dynamics of the system are governed by a perturbed nonlinear Schrodinger equation. The evolutions of amplitude and velocity of the soliton are found to be time independent, thereby admitting the lossless propagation of the electromagnetic soliton in the medium, which may have potential applications in soliton based optical communication systems. We also exploit the role of perturbation, which has a significant impact on the propagation of an electromagnetic soliton.

Effect of Varying Dzyaloshinskii—Moriya Interaction on the Bistable Nano-Scale Soliton Switching

The effect of Dzyaloshinskii—Moriya (D-M) interaction on the bistable nano-scale soliton switching offers the possiblity of developing a new innovative approach for data storage technology. The dynamics of Heisenberg ferromagnetic spin system is expressed in terms of generalized inhomogeneous higher order nonlinear Schrodinger (NLS) equation. The bistable soliton switching in the ferromagnetic medium is established by solving the associated coupled evolution equations for amplitude and velocity of the soliton using the fourth order Runge—Kutta method numerically.

Magnetization reversal in a site-dependent anisotropic Heisenberg ferromagnet under electromagnetic wave propagation

Abstract Information density and switching of magnetization offers an interesting physical phenomenon which invoke magneto-optical techniques employed on the magnetic medium. In this paper, we explore the soliton assisted magnetization reversal in the nanosecond regime in the theoretical framework of the Landau–Lifshitz–Maxwell (LLM) model. Starting from the Landau–Lifshitz equation, we employ the reductive perturbation method to derive an inhomogeneous nonlinear Schrödinger equation, governing the nonlinear spin excitations of a site-dependent anisotropic ferromagnetic medium under the influence of electromagnetic (EM) field in the classical continuum limit. From the results, it is found that the soliton undergoes a flipping thereby indicating the occurrence of magnetization reversal behavior in the nanoscale regime due to the presence of inhomogeneity in the form of a linear function. Besides, the spin components of magnetization are also evolved as soliton spin excitations.

Magnetization Reversal through a Soliton in a Site-Dependent Weak Ferromagnet

Magnetization reversal or switching is the process by which the magnetization of a specimen is changed from one stable direction into another. Switching the magnetization of a magnetic bit through the flipping of a soliton offers the possibility of developing a new innovative approach for data storage technologies. The spin dynamics of a site-dependent ferromagnet with the antisymmetric Dzyaloshinskii-Moriya interaction is governed by a generalized inhomogeneous higher order nonlinear Schrodinger equation. We demonstrate the magnetization reversal through the flipping of a soliton in the ferromagnetic medium by solving numerically the two coupled evolution equations for the velocity and amplitude of the soliton using the fourth order Runge-Kutta method. We propose a new approach for inducing the flipping behaviour of a soliton in the presence of an inhomogeneity by tuning the parameter associated with the Dzyaloshinskii-Moriya interaction, which causes the soliton to move with constant velocity and amplitude along the spin lattice.