Analytical theory of modulated magnetic solitons

Abstract

Droplet solitons are coherently precessing solitary waves that have been recently realized in thin ferromagnets with perpendicular anisotropy.In the strongly nonlinear regime, droplets can be well approximated by a slowly precessing, circular domain wall with a hyperbolic tangent form. Utilizing this representation, this work develops a general droplet modulation theory and applies it to study the long range effects of the magnetostatic field and a nanocontact spin torque oscillator (NC-STO) where spin polarized currents act as a gain source to counteract magnetic damping. An analysis of the dynamical equations for the droplet's center, frequency and phase demonstrates a negative processional frequency shift due to long range dipolar interactions, dependent on film thickness. Further analysis also demonstrates the onset of a saddle-node bifurcation at the minimum sustaining current for the NC-STO. The basin of attraction associated with the stable node demonstrates that spin torque enacts a restoring force to excursions of the droplet from the nanocontact center, observed previously in numerical simulations. Large excursions lead to the droplet's eventual decay into spin waves.

References in corpus (4)

• Theory for a dissipative droplet soliton excited by a spin torque nanocontact
• Propagation and control of nano-scale, magnetic droplet solitons
• Propagating two-dimensional magnetic droplets
• Effective anisotropy of thin nanomagnets: beyond the surface anisotropy approach

Cited by in corpus (11)

• Attraction, Merger, Reflection, and Annihilation in Magnetic Droplet Soliton Scattering
• Effects of thermal perturbations on magnetic dissipative droplet solitons
• Perturbation Theory for Propagating Magnetic Droplet Solitons
• Freezing and thawing magnetic droplet solitons
• Designing Magnetic Droplet Soliton Nucleation Employing Spin Polarizer
• Chiral excitations of magnetic droplet solitons driven by their own inertia
• Stochastic ejection of nanocontact droplet solitons via drift instability
• Propagating magnetic droplet solitons as moveable nanoscale spin-wave sources with tunable direction of emission
• Magnonic Band Structure Established by Chiral Spin-Density Waves in Thin Film Ferromagnets
• Thermal Activation Barriers for Creation and Annihilation of Magnetic Droplet Solitons in the Presence of Spin Transfer Torque
• Thermally Activated Transitions Between Micromagnetic States