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Current-driven dynamics of topological spin textures, such as skyrmions and antiskyrmions, have garnered considerable attention in condensed matter physics and spintronics. As compared with skyrmions, the current-driven dynamics of their antiparticles – antiskyrmions − remain less explored due to the increased complexity of antiskyrmions. Here, we design and employ fabricated microdevices of a prototypical antiskyrmion host, (Fe0.63Ni0.3Pd0.07)3P, to allow in situ current application with Lorentz transmission electron microscopy observations. The experimental results and related micromagnetic simulations demonstrate current-driven antiskyrmion dynamics confined within stripe domains. Under nanosecond-long current pulses, antiskyrmions exhibit directional motion along the stripe regardless of the current direction, while the antiskyrmion velocity is linearly proportional to the current density. Significantly, the antiskyrmion mobility could be enhanced when the current flow is perpendicular to the stripe direction. Our findings provide novel and reliable insights on dynamical antiskyrmions and their potential implications on spintronics. Antiskyrmions, like skyrmions, are a form of topological spin texture, with a topological charge of opposite sign to the equivalent skyrmion with the same polarity. While antiskyrmions have been less explored, they offer some potential advantages for applications, and here, Guang et al demonstrate antiskyrmion motion within stripe domains. [ABSTRACT FROM AUTHOR]

Atomic-scale observations of a specific local area would be considerably beneficial when exploring new fundamental materials and devices. The development of hardware-type aberration correction1,2 in electron microscopy has enabled local structural observations with atomic resolution3–5 as well as chemical and vibration analysis6–8. In magnetic imaging, however, atomic-level spin configurations are analysed by electron energy-loss spectroscopy by placing samples in strong magnetic fields9–11, which destroy the nature of the magnetic ordering in the samples. Although magnetic-field-free observations can visualize the intrinsic magnetic fields of an antiferromagnet by unit-cell averaging12, directly observing the magnetic field of an individual atomic layer of a non-uniform structure is challenging. Here we report that the magnetic fields of an individual lattice plane inside materials with a non-uniform structure can be observed under magnetic-field-free conditions by electron holography with a hardware-type aberration corrector assisted by post-digital aberration correction. The magnetic phases of the net magnetic moments of (111) lattice planes formed by opposite spin orderings between Fe3+ and Mo5+ in a ferrimagnetic double-perovskite oxide (Ba2FeMoO6) were successfully observed. This result opens the door to direct observations of the magnetic lattice in local areas, such as interfaces and grain boundaries, in many materials and devices.The magnetic fields of an individual lattice plane inside materials with a non-uniform structure were observed under magnetic-field-free conditions by electron holography. [ABSTRACT FROM AUTHOR]

In helimagnetic metals, ac current-driven spin motions can generate emergent electric fields acting on conduction electrons, leading to emergent electromagnetic induction (EEMI). Recent experiments reveal the EEMI signal generally shows a strongly current-nonlinear response. In this study, we investigate the EEMI of Tb5Sb3, a short-period helimagnet. Using small angle neutron scattering we show that Tb5Sb3 hosts highly disordered helimagnetism with a distribution of spin-helix periodicity. The current-nonlinear dynamics of the disordered spin helix in Tb5Sb3 indeed shows up as the nonlinear electrical resistivity (real part of ac resistivity), and even more clearly as a nonlinear and huge EEMI (imaginary part of ac resistivity) response. The magnitude of the EEMI reaches as large as several tens of μH for Tb5Sb3 devices on the scale of several tens of μm, originating to noncollinear spin textures possibly even without long-range helimagnetic order. Ac current-driven spin motions in helimagnetic metals can generate emergent electric fields acting on conduction electrons, leading to emergent electromagnetic induction (EEMI). In this study, we revealed that a short-period helimagnet Tb5Sb3 may have disordered spin helix structure and provides large EEMI. [ABSTRACT FROM AUTHOR]

The use of magnetic states in memory devices has a history dating back decades, and the experimental discovery of magnetic skyrmions and subsequent demonstrations of their control via magnetic fields, heat, and electric/thermal currents have ushered in a new era for spintronics research and development. Recent studies have experimentally discovered the antiskyrmion, the skyrmion's antiparticle, and while several host materials have been identified, control via thermal current remains elusive. In this work, we use thermal current to drive the transformation between skyrmions, antiskyrmions and non-topological bubbles, as well as the switching of helical states in the antiskyrmion-hosting ferromagnet (Fe0.63Ni0.3Pd0.07)3P at room temperature. We discover that a temperature gradient ∇ T drives a transformation from antiskyrmions to non-topological bubbles to skyrmions while under a magnetic field and observe the opposite, unidirectional transformation from skyrmions to antiskyrmions at zero-field, suggesting that the antiskyrmion, more so than the skyrmion, is robustly metastable at zero field. Topological spin textures, such as skyrmions and antiskyrmions are of interest for use in information storage, owing to their inherent robustness. Critical to this use is the ability to manipulate these spin textures. Here, Yasin et al. demonstrate heat current driven transformation of a topological spin texture in a ferromagnet at room temperature. [ABSTRACT FROM AUTHOR]

Driving and controlling single-skyrmion motion promises skyrmion-based spintronic applications. Recently progress has been made in moving skyrmionic bubbles in thin-film heterostructures and low-temperature chiral skyrmions in the FeGe helimagnet by electric current. Here, we report the motion tracking and control of a single skyrmion at room temperature in the chiral-lattice magnet Co9Zn9Mn2 using nanosecond current pulses. We have directly observed that the skyrmion Hall motion reverses its direction upon the reversal of skyrmion topological number using Lorentz transmission electron microscopy. Systematic measurements of the single-skyrmion trace as a function of electric current reveal a dynamic transition from the static pinned state to the linear flow motion via a creep event, in agreement with the theoretical prediction. We have clarified the role of skyrmion pinning and evaluated the intrinsic skyrmion Hall angle and the skyrmion velocity in the course of the dynamic transition. Our results pave a way to skyrmion applications in spintronic devices. Skyrmions, topological spin textures, have attracted interest for use in spin-based information processing. Here, Peng et al analyse the current driven motion of a single skyrmion at room temperature in a chiral-lattice magnet, tracking the motion using Lorentz transmission electron microscopy. [ABSTRACT FROM AUTHOR]

Thermal-current induced electron and spin dynamics in solids –dubbed "caloritronics"– have generated widespread interest in both fundamental physics and spintronics applications. Here, we examine the dynamics of nanometric topological spin textures, skyrmions driven by a temperature gradient ∇T or heat flow, that are evaluated through in-situ real-space observations in an insulating helimagnet Cu2OSeO3. We observe increases of the skyrmion velocity and the Hall angle with increasing ∇T above a critical value of ~ 13 mK/mm, which is two orders of magnitude lower than the ∇T required to drive ferromagnetic domain walls. A comparable magnitude of ∇T is also observed to move the domain walls between a skyrmion domain and the non-topological conical-spin domain from cold to hot regions. Our results demonstrate the efficient manipulation of skyrmions by temperature gradients, a promising step towards energy-efficient "green" spintronics. Skyrmions are a type of topological spin texture that great potential across a wide variety of technological applications. Here, Yu et al. study the thermally driven motion of Skyrmions and find a minimum temperature gradient for the motion of skyrmions two orders of magnitude smaller than for domain walls. [ABSTRACT FROM AUTHOR]

The electrical Hall effect can be significantly enhanced through the interplay of the conduction electrons with magnetism, which is known as the anomalous Hall effect (AHE). Whereas the mechanism related to band topology has been intensively studied towards energy efficient electronics, those related to electron scattering have received limited attention. Here we report the observation of giant AHE of electron-scattering origin in a chiral magnet MnGe thin film. The Hall conductivity and Hall angle, respectively, reach 40 , 000 Ω−1 cm−1 and 18 % in the ferromagnetic region, exceeding the conventional limits of AHE of intrinsic and extrinsic origins, respectively. A possible origin of the large AHE is attributed to a new type of skew-scattering via thermally excited spin-clusters with scalar spin chirality, which is corroborated by the temperature–magnetic-field profile of the AHE being sensitive to the film-thickness or magneto-crystalline anisotropy. Our results may open up a new platform to explore giant AHE responses in various systems, including frustrated magnets and thin-film heterostructures. The anomalous Hall effect (AHE) due to electron scattering process is typically limited to a small magnitude. Here, the authors report giant AHE of electron scattering origin in a chiral magnet MnGe thin film, possibly due to skew-scattering via thermally excited spin-clusters with scalar spin chirality. [ABSTRACT FROM AUTHOR]

Magnetic skyrmion textures are realized mainly in non-centrosymmetric, e.g. chiral or polar, magnets. Extending the field to centrosymmetric bulk materials is a rewarding challenge, where the released helicity/vorticity degree of freedom and higher skyrmion density result in intriguing new properties and enhanced functionality. We report here on the experimental observation of a skyrmion lattice (SkL) phase with large topological Hall effect and an incommensurate helical pitch as small as 2.8 nm in metallic Gd3Ru4Al12, which materializes a breathing kagomé lattice of Gadolinium moments. The magnetic structure of several ordered phases, including the SkL, is determined by resonant x-ray diffraction as well as small angle neutron scattering. The SkL and helical phases are also observed directly using Lorentz-transmission electron microscopy. Among several competing phases, the SkL is promoted over a low-temperature transverse conical state by thermal fluctuations in an intermediate range of magnetic fields. Understanding and controlling the skyrmion lattice (SkL) phase facilitates its versatile applications. Here the direct observation of a SkL phase with large topological Hall effect in centrosymmetric Gd3Ru4Al12 is reported, which is stabilized by thermal fluctuations and magnetic field without Dzyaloshinskii-Moriya interactions. [ABSTRACT FROM AUTHOR]

Skyrmions are nanoscale spin textures that are viewed as promising candidates as information carriers in future spintronic devices. Skyrmions have been observed using neutron scattering and microscopy techniques. Real-space imaging using electrons is a straightforward way to interpret spin configurations by detecting the phase shifts due to electromagnetic fields. Here, we report the first observation by electron holography of the magnetic flux and the three-dimensional spin configuration of a skyrmion lattice in Fe0.5Co0.5Si thin samples. The magnetic flux inside and outside a skyrmion was directly visualized and the handedness of the magnetic flux flow was found to be dependent on the direction of the applied magnetic field. The electron phase shifts φ in the helical and skyrmion phases were determined using samples with a stepped thickness t (from 55 nm to 510 nm), revealing a linear relationship (φ = 0.00173t). The phase measurements were used to estimate the three-dimensional structures of both the helical and skyrmion phases, demonstrating that electron holography is a useful tool for studying complex magnetic structures and for three-dimensional, real-space mapping of magnetic fields. [ABSTRACT FROM AUTHOR]

In helimagnetic metals, ac current-driven spin motions can generate emergent electric fields acting on conduction electrons, leading to emergent electromagnetic induction (EEMI). Recent experiments reveal the EEMI signal generally shows a strongly current-nonlinear response. In this study, we investigate the EEMI of Tb 5 Sb 3 , a short-period helimagnet. Using small angle neutron scattering we show that Tb 5 Sb 3 hosts highly disordered helimagnetism with a distribution of spin-helix periodicity. The current-nonlinear dynamics of the disordered spin helix in Tb 5 Sb 3 indeed shows up as the nonlinear electrical resistivity (real part of ac resistivity), and even more clearly as a nonlinear and huge EEMI (imaginary part of ac resistivity) response. The magnitude of the EEMI reaches as large as several tens of μH for Tb5Sb3 devices on the scale of several tens of μm, originating to noncollinear spin textures possibly even without long-range helimagnetic order., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s) 2024.)