Suppression of the skyrmion Hall effect in planar nanomagnets by the magnetic properties engineering: Skyrmion transport on nanotracks with magnetic strips

Abstract

Micromagnetic simulations have been performed to investigate the suppression of the skyrmion Hall effect in nanotracks with their magnetic properties strategically modified. In particular, we study two categories of magnetically modified nanotracks. One of them, repulsive edges have been inserted in the nanotrack and, in the other, an attractive strip has been placed exactly on the longest axis of the nanotrack. Attractive and repulsive interactions can be generated from the engineering of magnetic properties. For instance, it is known that the skyrmion can be attracted to a region where the exchange stiffness constant is decreased. On the other hand, the skyrmion can be repelled from a region characterized by a local increase in the exchange stiffness constant. In order to provide a background for experimental studies, we vary not only the magnetic material parameters (exchange stiffness, perpendicular magnetocrystalline anisotropy and the Dzyaloshinskii-Moriya constant) but also the width of the region magnetically modified, containing either a local reduction or a local increase for each one of these magnetic properties. In the numerical simulations, the skyrmion motion was induced by a spin-polarized current and the found results indicate that it is possible to transport skyrmions around the longest axis of the nanotrack. In practice, the skyrmion Hall effect can be completely suppressed in magnetic nanotracks with strategically modified magnetic properties. Furthermore, we discuss in detail 6 ways to suppress the skyrmion Hall effect by the usage of nanotracks with repulsive edges and nanotracks with an attractive strip.

Quantitative behavior study of velocity, radius and topological charge on skyrmion/edge interaction dynamics on Co/Pt nanotrack

“…In previous works, our group observed that the local decrease (increase) of the exchange stiffness constant acts as an attraction (repulsion) pinning center to a vortex, domain wall or skyrmion [33,34,41,42]. In two recent works [43,44] we showed other three ways to build magnetic skyrmion traps using magnetic defects, as variation in magnetocrystalline anisotropy, in DM interaction and in dipolar constant. Recently, we proposed several ways of suppression the skyrmion Hall effect in ferromagnetic nanotracks with their magnetic properties strategically modified [44].…”

“…Once Co/Pt multilayers allow the emergence of Néel-type skyrmions (hedgehog-type configuration), the magnetic configuration with a single skyrmion here been chosen as initial condition, by considering an analytical solution in which a Néel skyrmion is placed in a suitable position on the nanotrack. A description of the analytical model for skyrmions in nanotracks can be found in reference [44]. In the absence of a magnetic field or spin polarized current, the integration of the LLG equation leads to the stable configuration.…”

“…In two recent works [43,44] we showed other three ways to build magnetic skyrmion traps using magnetic defects, as variation in magnetocrystalline anisotropy, in DM interaction and in dipolar constant. Recently, we proposed several ways of suppression the skyrmion Hall effect in ferromagnetic nanotracks with their magnetic properties strategically modified [44].…”

Skyrmion bound state and dynamics in an antiferromagnetic bilayer racetrack

“…This phenomenon is called skyrmion Hall effect (SHE) [20][21][22]. A number of proposals has appeared to bypass such an effect, for instance, the use of engineered materials [23,24], the substitution of skyrmions by other topological magnetic structures as information carriers [25], and the coupling of skyrmions in magnetic bilayers [26][27][28][29][30].…”

Engineering antiferromagnetic skyrmions and antiskyrmions at metallic interfaces

“…Despite many advantages associated with skyrmions, such as, enhanced stability due to its topological protection [8][9][10][11][12][13], ultra-low current density dynamics [14][15][16][17][18], and large Hall current [19,20], their transverse deflection upon application of current -known as skyrmion Hall effect -presents a major bottleneck for applications [21]. Therefore, reducing the transverse component of skyrmion velocity while retaining all of its favorable properties is an important goal of research in this field [22][23][24]. One of the approaches has been to tune the nature of the skyrmion state in such a way that the magnus force gets intrinsically canceled [25][26][27].…”