Generation and stability of dynamical skyrmions and droplet solitons

TL;DR

This paper investigates the formation and stability of droplet solitons and dynamical skyrmions in magnetic films driven by spin-polarized currents, highlighting conditions that favor each and their electrical signatures.

Contribution

It identifies key factors influencing whether droplet solitons or dynamical skyrmions form and demonstrates the greater stability of skyrmions in such systems.

Findings

Dynamical skyrmions are more stable than droplets.

Oersted fields and initial magnetization influence object formation.

Electrical signatures can distinguish between droplets and skyrmions.

Abstract

A spin-polarized current in a nanocontact to a magnetic film can create collective magnetic oscillations by compensating the magnetic damping. In particular, in materials with uniaxial magnetic anisotropy, droplet solitons have been observed a self-localized excitation consisting of partially reversed magnetization that precesses coherently in the nanocontact region. It is also possible to generate topological droplet solitons, known as \emph{dynamical skyrmions}. Here we study the conditions that promote either droplet or dynamical skyrmion formation and describe their stability in magnetic films without Dzyaloshinskii-Moriya interactions. We show that Oersted fields from the applied current as well as the initial magnetization state can determine whether a droplet or dynamical skyrmion forms. Dynamical skyrmions are found to be more stable than droplets. We also discuss electrical characteristics that can be used distinguish these magnetic objects.