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The design of complex, competing effects in magnetic systems—be it via the introduction of nonlinear interactions 1 – 4 , or the patterning of three-dimensional geometries 5 , 6 —is an emerging route to achieve new functionalities. In particular, through the design of three-dimensional geometries and curvature, intrastructure properties such as anisotropy and chirality, both geometry-induced and intrinsic, can be directly controlled, leading to a host of new physics and functionalities, such as three-dimensional chiral spin states 7 , ultrafast chiral domain wall dynamics 8 – 10 and spin textures with new spin topologies 7 , 11 . Here, we advance beyond the control of intrastructure properties in three dimensions and tailor the magnetostatic coupling of neighbouring magnetic structures, an interstructure property that allows us to generate complex textures in the magnetic stray field. For this, we harness direct write nanofabrication techniques, creating intertwined nanomagnetic cobalt double helices, where curvature, torsion, chirality and magnetic coupling are jointly exploited. By reconstructing the three-dimensional vectorial magnetic state of the double helices with soft-X-ray magnetic laminography 12 , 13 , we identify the presence of a regular array of highly coupled locked domain wall pairs in neighbouring helices. Micromagnetic simulations reveal that the magnetization configuration leads to the formation of an array of complex textures in the magnetic induction, consisting of vortices in the magnetization and antivortices in free space, which together form an effective B field cross-tie wall 14 . The design and creation of complex three-dimensional magnetic field nanotextures opens new possibilities for smart materials 15 , unconventional computing 2 , 16 , particle trapping 17 , 18 and magnetic imaging 19 . In magnetic double nanohelices, the balance of geometrical effects and dipolar interaction results in strongly coupled three-dimensional spin states. This leads to topological features in the stray field, offering a new route to pattern the magnetic induction.

Magnetic skyrmions are topologically non-trivial nanoscale objects. Their topology, which originates in their chiral domain wall winding, governs their unique response to a motion-inducing force. When subjected to an electrical current, the chiral winding of the spin texture leads to a deflection of the skyrmion trajectory, characterised by an angle with respect to the applied force direction. This skyrmion Hall angle is predicted to be skyrmion diameter-dependent. In contrast, our experimental study finds that the skyrmion Hall angle is diameter-independent for skyrmions with diameters ranging from 35 to 825 nm. At an average velocity of 6 ± 1 ms −1 , the average skyrmion Hall angle was measured to be 9° ± 2°. In fact, the skyrmion dynamics is dominated by the local energy landscape such as materials defects and the local magnetic configuration. Magnetic skyrmions are promising objects for future spintronic devices. However, a better understanding of their dynamics is required. Here, the authors show that in contrast to predictions the skyrmion Hall angle is independent of their diameter and motion is dominated by disorder and skyrmion-skyrmion interactions in the system.

Understanding and control of the dynamic response of magnetic materials with a three-dimensional magnetization distribution is important both fundamentally and for technological applications. From a fundamental point of view, the internal magnetic structure and dynamics in bulk materials still need to be mapped1, including the dynamic properties of topological structures such as vortices2, magnetic singularities3 or skyrmion lattices4. From a technological point of view, the response of inductive materials to magnetic fields and spin-polarized currents is essential for magnetic sensors and data storage devices5. Here, we demonstrate time-resolved magnetic laminography, a pump–probe technique, which offers access to the temporal evolution of a three-dimensional magnetic microdisc with nanoscale resolution, and with a synchrotron-limited temporal resolution of 70 ps. We image the dynamic response to a 500 MHz magnetic field of the complex three-dimensional magnetization in a two-phase bulk magnet with a lateral spatial resolution of 50 nm. This is achieved with a stroboscopic measurement consisting of eight time steps evenly spaced over 2 ns. These measurements map the spatial transition between domain wall motion and the dynamics of a uniform magnetic domain that is attributed to variations in the magnetization state across the phase boundary. Our technique, which probes three-dimensional magnetic structures with temporal resolution, enables the experimental investigation of functionalities arising from dynamic phenomena in bulk and three-dimensional patterned nanomagnets6.Knowledge and control of the dynamic response in micromagnetic configurations is important both for understanding their fundamental properties and for their use in technological applications. Pump–probe magnetic laminography now unveils the evolution of the magnetization in a three-dimensional system with nanoscale resolution.

Magnetic skyrmions are topologically protected spin textures that have nanoscale dimensions and can be manipulated by an electric current. These properties make the structures potential information carriers in data storage, processing and transmission devices. However, the development of functional all-electrical electronic devices based on skyrmions remains challenging. Here we show that the current-induced creation, motion, detection and deletion of skyrmions at room temperature can be used to mimic the potentiation and depression behaviours of biological synapses. In particular, the accumulation and dissipation of magnetic skyrmions in ferrimagnetic multilayers can be controlled with electrical pulses to represent the variations in the synaptic weights. Using chip-level simulations, we demonstrate that such artificial synapses based on magnetic skyrmions could be used for neuromorphic computing tasks such as pattern recognition. For a handwritten pattern dataset, our system achieves a recognition accuracy of ~89%, which is comparable to the accuracy achieved with software-based ideal training (~93%). The electrical current-induced creation, motion, detection and deletion of skyrmions in ferrimagnetic multilayers can be used to mimic the behaviour of biological synapses, providing devices that could be used for neuromorphic computing tasks such as pattern recognition.

Ferrimagnetic alloys are model systems for understanding the ultrafast magnetization switching in materials with antiferromagnetically coupled sublattices. Here we investigate the dynamics of the rare-earth and transition-metal sublattices in ferrimagnetic GdFeCo and TbCo dots excited by spin–orbit torques with combined temporal, spatial and elemental resolution. We observe distinct switching regimes in which the magnetizations of the two sublattices either remain synchronized throughout the reversal process or switch following different trajectories in time and space. In the latter case, we observe a transient ferromagnetic state that lasts up to 2 ns. The asynchronous switching of the two magnetizations is ascribed to the master–agent dynamics induced by the spin–orbit torques on the transition-metal and rare-earth sublattices and their weak antiferromagnetic coupling, which depends sensitively on the alloy microstructure. Larger antiferromagnetic exchange leads to faster switching and shorter recovery of the magnetization after a current pulse. Our findings provide insight into the dynamics of ferrimagnets and the design of spintronic devices with fast and uniform switching. Asynchronous sublattice magnetization switching is found in a ferrimagnetic material and understood by considering the exchange coupling and alloy microstructure.

Magnetic skyrmions are topological spin textures that hold great promise as nanoscale information carriers in non-volatile memory and logic devices. While room-temperature magnetic skyrmions and their current-induced motion were recently demonstrated, the stray field resulting from their finite magnetisation and their topological charge limit their minimum size and reliable motion. Antiferromagnetic skyrmions allow to lift these limitations owing to their vanishing magnetisation and net zero topological charge, promising ultra-small and ultra-fast skyrmions. Here, we report on the observation of isolated skyrmions in compensated synthetic antiferromagnets at zero field and room temperature using X-ray magnetic microscopy. Micromagnetic simulations and an analytical model confirm the chiral antiferromagnetic nature of these skyrmions and allow the identification of the physical mechanisms controlling their size and stability. Finally, we demonstrate the nucleation of synthetic antiferromagnetic skyrmions via local current injection and ultra-fast laser excitation. Skyrmions in synthetic antiferromagnets are appealing for use in future memory and computing devices, combining small size and fast motion, but creating, stabilizing, and observing them remains a challenge. Here, Juge et al demonstrate the stabilization and current and light induced nucleation of skyrmions in a synthetic antiferromagnet, observing the magnetization texture in each layer using X-ray magnetic microscopy.

Spin waves are collective perturbations in the orientation of the magnetic moments in magnetically ordered materials. Their rich phenomenology is intrinsically three-dimensional; however, the three-dimensional imaging of spin waves has so far not been possible. Here, we image the three-dimensional dynamics of spin waves excited in a synthetic antiferromagnet, with nanoscale spatial resolution and sub-ns temporal resolution, using time-resolved magnetic laminography. In this way, we map the distribution of the spin-wave modes throughout the volume of the structure, revealing unexpected depth-dependent profiles originating from the interlayer dipolar interaction. We experimentally demonstrate the existence of complex three-dimensional interference patterns and analyze them via micromagnetic modelling. We find that these patterns are generated by the superposition of spin waves with non-uniform amplitude profiles, and that their features can be controlled by tuning the composition and structure of the magnetic system. Our results open unforeseen possibilities for the study and manipulation of complex spin-wave modes within nanostructures and magnonic devices. The techniques we typically employ to study spin-waves in magnetic materials, such as Brillouin Light Scattering, are two-dimensional. Spin waves, however, are manifestly three-dimensional. Here, Girardi et al. succeed in such three-dimensional imaging of spin waves in a synthetic antiferromagnet using Time-Resolved Soft X-ray Laminography.

While the general effects of experimental conditions such as photon flux and sample thickness on the quality of data acquired by scanning transmission X‐ray microscopy (STXM) are widely known at a basic level, the specific details are rarely discussed. This leaves the community open to forming misconceptions that can lead to poor decisions in the design and execution of STXM measurements. A formal treatment of the uncertainty and distortions of transmission signals (due to dark counts, higher‐order photons and poor spatial or spectral resolution) is presented here to provide a rational basis for the pursuit of maximizing data quality in STXM experiments. While we find an optimum sample optical density of 2.2 in ideal conditions, the distortions considered tend to have a stronger effect for thicker samples and so ∼1 optical density at the analytical energy is recommended, or perhaps even thinner if significant distortion effects are expected (e.g. lots of higher‐order light is present in the instrument). (Note that X‐ray absorption calculations based on simple elemental composition do not include near‐edge resonances and so cannot accurately represent the spectral resonances typically employed for contrast in STXM.) Further, we present a method for objectively assessing the merits of higher‐order suppression in terms of its impact on the quality of transmission measurements that should be useful for the design of synchrotron beamlines. Quantifying sources of error in X‐ray transmission measurements provides objective guidance for questions of optimum sample thickness and beamline configuration for higher‐order suppression.

The magnetoelastic effect—the change of magnetic properties caused by the elastic deformation of a magnetic material—has been proposed as an alternative approach to magnetic fields for the low-power control of magnetization states of nanoelements since it avoids charge currents, which entail ohmic losses. Here, we have studied the effect of dynamic strain accompanying a surface acoustic wave on magnetic nanostructures in thermal equilibrium. We have developed an experimental technique based on stroboscopic X-ray microscopy that provides a pathway to the quantitative study of strain waves and magnetization at the nanoscale. We have simultaneously imaged the evolution of both strain and magnetization dynamics of nanostructures at the picosecond time scale and found that magnetization modes have a delayed response to the strain modes, adjustable by the magnetic domain configuration. Our results provide fundamental insight into magnetoelastic coupling in nanostructures and have implications for the design of strain-controlled magnetostrictive nano-devices. Understanding the effects of local dynamic strain on magnetization may help the development of magnetic devices. Foerster et al. demonstrate stroboscopic imaging that allows the observation of both strain and magnetization dynamics in nickel when surface acoustic waves are driven in the substrate.

Magnonics is gaining momentum as an emerging technology for information processing. The wave character and Joule heating-free propagation of spin-waves hold promises for highly efficient computing platforms, based on integrated magnonic circuits. The realization of such nanoscale circuitry is crucial, although extremely challenging due to the difficulty of tailoring the nanoscopic magnetic properties with conventional approaches. Here we experimentally realize a nanoscale reconfigurable spin-wave circuitry by using patterned spin-textures. By space and time-resolved scanning transmission X-ray microscopy imaging, we directly visualize the channeling and steering of propagating spin-waves in arbitrarily shaped nanomagnonic waveguides, with no need for external magnetic fields or currents. Furthermore, we demonstrate a prototypic circuit based on two converging nanowaveguides, allowing for the tunable spatial superposition and interference of confined spin-waves modes. This work paves the way to the use of engineered spin-textures as building blocks of spin-wave based computing devices. Magnonics is gaining momentum as an emerging technology for information processing. The authors experimentally demonstrated spin-wave propagation within nanopatterned circuits based on domain walls, using time-resolved scanning transmission X-ray microscopy imaging.