The topological (anti)skyrmion configurations have presented promise for versatile spintronic applications in racetrack memory, logic gates, and bio-inspired computing due to the nontrivial spin topology and convenient current-driven dynamics. However, the precise control of (anti)skyrmion-based information unit transportation via electric current in conquer of skyrmion Hall effect remains challenging especially in ferromagnetic films, limiting their integration into spintronic devices. In this study, we demonstrate the density, velocity, and direction control of half-skyrmion, with a topological charge of 1/2, in a predictable and governable way under the stimuli of electric current in Pt/Co/Ta multilayers. The particular nonsymmetric configuration of half-skyrmion introduces variable competing forces under joint manipulation of magnetic field and electric current. Thereby, the half-skyrmion application with highly controllable dynamic behavior is further proposed in prototype devices such as half-skyrmionic racetrack memory device with parallelized operation, programmable logic devices, and neuromorphic computing artificial synapses. This work sheds light on the versatile spintronic applications of half-skyrmions through electromagnetic coordinated manipulation.

Magnetic skyrmions are topologically protected quasiparticles that are promising for applications in spintronics. However, the low stability of most magnetic skyrmions leads to either a narrow temperature range in which they can exist, a low density of skyrmions, or the need for an external magnetic field, which greatly limits their wide application. In this study, high-density, spontaneous magnetic biskyrmions existing within a wide temperature range and without the need for a magnetic field were formed in ferrimagnets owing to the existence of a negative thermal expansion of the lattice. Moreover, a strong connection between the atomic-scale ferrimagnetic structure and nanoscale magnetic domains in Ho(Co,Fe)3 was revealed via in situ neutron powder diffraction and Lorentz transmission electron microscopy measurements. The critical role of the negative thermal expansion in generating biskyrmions in HoCo3 based on the magnetoelastic coupling effect is further demonstrated by comparing the behavior of HoCo2.8Fe0.2 with a positive thermal expansion.

We report the observation of angular-dependent antisymmetric magnetoresistance (MR) in artificially deformed Co-Tb Hall bar structures with perpendicular magnetization. Simultaneous transport measurements and domain imaging show that the antisymmetric MR results from the generation of a single domain wall (DW) inclination due to the restricted geometry and is further proportional to the inclination-associated geometry factor. The results are well described by a theoretical model that is supported by analytic and numerical calculations of the nonequilibrium current and Hall voltage distribution in the vicinity of the inclined DW. This finding provides a straightforward and effective approach to control DW geometries, leading to various DW-based spintronic device applications.

Rare-earth RMn6Sn6 magnets reattract the attention due to their recently discovered topological properties in a strong correlation with a kagome magnetic lattice and different rare-earth magnetic elements. To understand the microscopic mechanism and discover topological spin textures, we report here the real-space observation of temperature-induced spin reorientation transition in RMn6Sn6 (R = Ho, Dy) magnets. The magnetic domain evolution corresponding to the magnetization deviation from the ab-plane into a cone state is in situ demonstrated by using Lorenz transmission electron microscopy and, moreover, individual biskyrmions are generated at room temperature under an external magnetic field in DyMn6Sn6.

The antisymmetric magnetoresistance (MR) and anomalous Hall effect (AHE) of perpendicularly magnetized Co 1− x Tb x thin films with different Tb concentration have been investigated under gradient magnetic fields. Owing to the presence of tilting domain walls, the Co 1− x Tb x films exhibit anomalous antisymmetric MR, whose polarity reversal is strongly dependent on the film composition and exactly consistent with the simultaneously measured AHE. Our results suggest that the effect of disorder scattering from impurities and dispersive domain wall boundaries is more pronounced in Co 1− x Tb x alloy films distant from the compensation point. Moreover, the modulation of AHE coefficient Rs directly leads to the remarkable variation of antisymmetric MR, providing a new insight into design of domain wall based electronic devices.

We demonstrate the generation of mixed-type skyrmions (all are about 200 nm) that are primarily Bloch-type, hybrid-type, and a negligible amount of Néel-type in symmetric Pt/Co(1.55)/Pt multilayers at room temperature. The magnetic field dependence of skyrmion evolution is reversible. Brillouin light-scattering is used to quantitatively quantify the Dzyaloshinskii-Moriya interaction constant D in order to comprehend the mechanism. Interestingly, the D value is high enough to generate skyrmions in a symmetric sandwich structure. Micromagnetic simulations show that Néel-type skyrmions transform into Bloch-type skyrmions as the D value decreases. The interface-induced non-uniform D may be the cause to generate mixed-type skyrmions. This work broadens the flexibility to generate skyrmions by engineering skyrmion-based devices with nominally symmetric multilayers without the requirement of very large DMI.