Magnetic kπ-skyrmions are rotationally symmetric vortex-like solitons, whose magnetization rotates by an angle of kπ from its center to outermost boundary. Here, we report kπ-skyrmions (k = 2, 3, and ...4) and their field-driven magnetic evolutions in centrosymmetric uniaxial ferromagnetic Fe3Sn2 nanodisks. We show that zero-field non-axisymmetric kπ-skyrmions turn to be axisymmetric after applying an out-of-plane field. The collapses of (k+1)π-skyrmions to kπ-skyrmions induced by external field are also experimentally identified. Furthermore, numerical simulations well reproduce experimental magnetization mapping of kπ-skyrmions and further demonstrate their three-dimensional magnetic structures.
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Magnetic skyrmions have attracted enormous research interest since their discovery a decade ago. The non-trivial real-space topology of these nano-whirls leads to fundamentally interesting and ...technologically relevant consequences — the skyrmion Hall effect of the texture and the topological Hall effect of the electrons. Furthermore, it grants skyrmions in a ferromagnetic surrounding great stability even at small sizes, making skyrmions aspirants to become the carriers of information in the future. Still, the utilization of skyrmions in spintronic devices has not been achieved yet, among other reasons, due to shortcomings in their current-driven motion. In this review, we present recent trends in the field of topological spin textures that go beyond skyrmions. The majority of these objects can be considered a combination of multiple subparticles, such as the bimeron, or the skyrmion analogues in different magnetic surroundings, such as antiferromagnetic skyrmions, as well as three-dimensional generalizations, such as hopfions. We classify the alternative magnetic quasiparticles – some of them observed experimentally, others theoretical predictions – and present the most relevant and auspicious advantages of this emerging field.
The question of the dependence of the topological charge q of a gauged Skyrmion, on the gauge field, is studied quantitatively. Two examples, both gauged with SO(2) are studied and contrasted: i) The ...O(3) model in 2+1 dimensions, and ii) The O(4) model in 3+1 dimensions. In case i), where the (usual) Chern–Simons (CS) term is present, the value of q changes sign, going through zero. This evolution is tracked by a parameter characterising the solutions in the given theory. In case ii), in which dimensions no CS density is available, the evolution of q is not observed.
Abstract
The profile, radius, and energy of chiral skyrmions, found in magnetic materials with the Dzyaloshinskii–Moriya (DM) interaction and easy-axis anisotropy perpendicular to the film, have been ...previously calculated in the asymptotic limits of small and large skyrmion radius, as functions of the model parameter. We extend the asymptotic analysis to the case of an external field or a combination of anisotropy and external field. The formulae for the skyrmion radius and energy are then modified, by the use of fitting techniques, into very good approximations through almost the entire range of skyrmion radii, from zero to infinity. We include a study of the effect of the magnetostatic field on the skyrmion profile in two cases. We compare the profile of magnetic bubbles, stabilized without the chiral DM interaction to that of a chiral skyrmion.
Skyrmions have attracted a great attention in spintronics because of their potential use as robust information carriers with distinctive protection. Though the realization of skyrmion‐based devices ...requires flexible control of a skyrmion motion, achieving such a skyrmion motion has been hampered by the skyrmion Hall effect (SkHE), which refers to the presence of a finite angle between a current and the skyrmion trajectory. Here, new insight for the precise control of half‐skyrmion motion is presented, including complete suppression of the SkHE by deforming the internal structure of skyrmions, which is experimentally achieved by external magnetic field to steer current‐driven half‐skyrmions in the desired direction. Furthermore, based on the unique advantages in half‐skyrmions, the potential of half‐skyrmions application beyond skyrmion‐based electronics is also demonstrated by presenting simple half‐skyrmion‐based addition/subtraction operation. The findings of controllability of 2D half‐skyrmion motion will provide new perspectives on utilization of topological solitons for device applications.
Precise control of a half‐skyrmion motion by deforming the internal structure of skyrmions is experimentally and theoretically demonstrated by utilizing external magnetic field. Furthermore, the distinct advantages of half‐skyrmions help to realize the potential of half‐skyrmions application beyond skyrmion‐based electronics by introducing addition/subtraction operation.
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