Non-linear dynamics and two-dimensional solitons for spin $S=1$ ferromagnets with biquadratic exchange

Abstract

We develop a consistent semiclassical theory of spin dynamics for an isotropic ferromagnet with a spin $S=1$ taking into consideration both bilinear and biquadratic over spin operators exchange interaction. For such non-Heisenberg magnets, a peculiar class of spin oscillations and waves, for which the quantum spin expectation value $\mathbf{m}=<\mathbf{S}>$ does not change it direction, but changes in length, is presented. Such ``longitudinal'' excitations do not exist in regular magnets, dynamics of which are described in terms of the Landau-Lifshitz equation or by means of the spin Heisenberg Hamiltonian. We demonstrate the presence of non-linear uniform oscillations and waves, as well as self-localized dynamical excitations (solitons) with finite energy. A possibility of excitation of such oscillations by ultrafast laser pulse is discussed.

11 pages, 7 figures, MikTEX

References in corpus (6)

• Nonequilibrium Magnetization Dynamics of Nickel
• Effective field theory for S=1 quantum nematic
• Probable absence of a quadrupolar spin-nematic phase in the bilinear-biquadratic spin-1 chain
• Topological solitons in highly anisotropic two dimensional ferromagnets
• Dipole and Quadrupole Skyrmions in S=1 (Pseudo)Spin Systems
• Quantum effects for the 2D soliton in isotropic ferromagnets

Cited by in corpus (5)

• Dynamics and relaxation in spin nematics
• Phase transitions in the two-dimensional Anisotropic Biquadratic Heisenberg Model
• Study of the bilinear biquadratic Heisenberg model on a honeycomb lattice via Schwinger bosons
• Dark solitons in ferromagnetic chains with first- and second-neighbor interactions
• Semiclassical description of anisotropic magnets for spin S=1