Permanent magnets containing rare earth elements are essential components for the electrification of society. Ce(Co1-xCux)(5) permanent magnets are a model system known for their substantial coercivity, yet the underlying mechanism remains unclear. Here, we investigate Ce(Co0.8Cu0.2)(5.4) magnets with a coercivity of similar to 1 T. Using transmission electron microscopy (TEM) and atom probe tomography (APT), we identify a nanoscale cellular structure formed by spinodal decomposition. Cu-poor cylindrical cells (similar to 5-10 nm in diameter, similar to 20 nm long) have a disordered CeCo5-type structure and a composition Ce(Co0.9Cu0.1)(5.3). Cu-rich cell boundaries are similar to 5 nm thick and exhibit a modified CeCo5 structure, with Cu ordered on the Co sites and a composition Ce(Co0.7Cu0.3)(5.0). Micromagnetic simulations demonstrate that the intrinsic Cu concentration gradients up to 12 at.% Cu/nm lead to a spatial variation in magnetocrystalline anisotropy and domain wall energy, resulting in effective pinning and high coercivity. Compared to Sm2Co17-type magnets, Ce(Co0.8Cu0.2)(5.4) displays a finer-scale variation of conventional pinning with lower structural and chemical contrast in its underlying nanostructure. The identification of nanoscale chemical segregation in nearly single-phase Ce(Co0.8Cu0.2)(5.4) magnets provides a microstructural basis for the long-standing phenomenon of "giant intrinsic magnetic hardness" in systems such as SmCo5-xMx, highlighting avenues for designing rare-earth-lean permanent magnets via controlled nanoscale segregation.

Fe‐rich high‐voltage spinels are attractive positive electrode materials for next‐generation Li‐ion batteries that offer high resource efficiency and high operating voltages. However, Fe‐rich high‐voltage spinels do not provide stable cycling performance, especially when compared to the Ni‐ and Co‐rich members of the high‐voltage spinel family. To understand the failure mechanism of Fe‐rich high‐voltage spinels, the impact of Ni stabilization on the solid solutions LiNixFe0.5−xMn1.5O4 (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) is followed. Electrochemical analysis shows that stable cycling performance can be achieved at relatively low Ni substitution (x = 0.2). Rietveld and pair distribution function analysis show remarkable similarity in average and local structural features, supported by 4D scanning transmission electron microscopy. The cycling mechanism of LiFe0.5Mn1.5O4 and Ni‐stabilized LiNi0.2Fe0.3Mn1.5O4 is further compared via in situ powder X‐ray diffraction and in situ diffuse reflectance infrared Fourier transform spectroscopy. It is found that the presence of Ni in the electrodes leads to favorable electrolyte–electrode interactions that suppress oxidative reactions and the formation of large concentration polarizations, which is the predominant failure mechanism of LiFe0.5Mn1.5O4.

Van der Waals (vdW) magnetic heterostructures offer a versatile platform for engineering interfacial spin interactions with atomic precision, enabling nontrivial spin textures and dynamics behavior. In this work, robust asymmetric magnetization reversal and exchange bias are reported in Fe3GeTe2 (FGT), driven by interlayer exchange coupling with the A-type antiferromagnet CrSBr. Despite the orthogonal magnetic anisotropies-out-of-plane easy axis in FGT and in-plane in CrSBr-a strong interfacial exchange interaction that gives rise to pronounced and switchable exchange bias and asymmetric switching in FGT is observed, persisting up to the Néel temperature of CrSBr (∼132 K) as revealed by anomalous Hall effect measurements. The microscopic origin of this behavior is uncovered through cross-sectional magnetic imaging of the domain structure using off-axis electron holography. The results reveal that the asymmetric switching and exchange bias arise from the influence of CrSBr on the domain configuration of FGT, where the in-plane antiferromagnetic state of CrSBr promotes the formation of stripe-like domain structures in FGT with circular rotation of magnetization in the cross-sectional bc plane defined by the easy axes of both FGT and CrSBr. These findings elucidate the mechanism of exchange bias in orthogonally coupled vdW systems and demonstrate a pathway for stabilizing 3D domain structures in ferromagnets through interfacial exchange interactions.

Solid oxide cells (SOCs) are likely to play crucial role in the green energy transition, but their widespread adoption is hindered by degradation issues, particularly catalyst agglomeration. Nanoparticle exsolution in double-perovskite materials offers a promising solution by creating electrode materials with stable metallic nanocatalysts strongly bonded to the parent oxide, mitigating high-temperature agglomeration issues. Thus, understanding the dynamic evolution of microstructure and catalytic behavior in such materials is vital for developing high-performing SOC catalysts. This study utilized a multimodal approach to investigate the dynamics of exsolution in Sr2FeMo0.65Ni0.35O6-delta (SFM-Ni) and its effect on cell performance. In situ environmental transmission electron microscopy (ETEM), in situ transmission electron microscopy (TEM) coupled with mass spectrometry visualized the formation and the stability of exsolved particles especially at the concave faces of the parent material during chemical conversion of CO from CO2. Simultaneously, macro-scale cell experiments coupled with electrochemical impedance spectroscopy, and focused ion beam-scanning electron microscopy (FIB-SEM) tomography, apart from verifying the nanoscale observations, provided crucial insights into the correlation between the exsolution process observed at the micro-scale and the overall cell performance. These findings offers valuable insights into the design and optimization of improved electrode materials for SOCs. Understanding the dynamic behavior of exsolved catalysts would help in enhancing the electrochemical performance at both the nano and macro levels, ultimately advancing the field of sustainable energy technologies.

Antimony sulfide (Sb2S3), a compound of earth-abundant elements with a highly anisotropic, quasi-layered crystal structure, has triggered growing interest as a solar absorber in photovoltaics and as a phase-change material in memory devices. However, challenges remain in achieving high-quality thin films with controlled nucleation and growth for optimal performance. Here, we investigate the phase transformation, crystal structure and properties, as well as the growth and degradation of atomic layer-deposited Sb2S3 thin films using in situ TEM and correlative ex situ analysis. The as-deposited amorphous films crystallized at 243 °C, forming grains with an [100] out-of-plane texture that developed into tens to hundreds of micrometer-long, leaf-shaped grains. Introducing an ultrathin ZnS interfacial layer increased nucleation density, resulting in few-micrometer-sized, more uniform grains while retaining the overall [100] texture. In situ observations and subsequent crystal orientation analysis with cutting-edge 4D-STEM and EBSD revealed that the grains grew faster along the [010] ribbon direction and that the bare films underwent early-stage degradation, forming holes in amorphous regions during annealing. The ZnS interlayer mitigated degradation, stabilizing the films and improving their uniformity. These findings offer valuable insights for optimizing Sb2S3 thin films for applications as both solar cell materials and phase-change materials.

Small adjustments in atomic configurations can significantly impact the magnetic properties of matter. Strain, for instance, can alter magnetic anisotropy and enable fine-tuning of magnetism. However, the effects of these changes on nanoscale magnetism remain largely unexplored. In particular, when strain fluctuates at the nanoscale, directly linking structural changes with magnetic behavior poses a substantial challenge. Here, we develop an approach, LA-Ltz-4D-STEM, to map structural information and magnetic fields simultaneously at the nanoscale. This approach opens avenues for an in-depth study of structure-property correlations of magnetic materials at the nanoscale. We applied LA-Ltz-4D-STEM to image strain, atomic packing, and magnetic fields simultaneously in a deformed amorphous ferromagnet with complex strain variations at the nanoscale. An anomalous magnetic configuration near shear bands, which reside in a magnetostatically high-energy state, was observed. By performing pixel-to-pixel correlation of the different physical quantities across a large field of view, a critical aspect for investigating industrial ferromagnetic materials, the magnetic moments were classified into two distinct groups: one influenced by magnetoelastic coupling and the other oriented by competition with magnetostatic energy. The authors present an approach to simultaneously map local magnetization, strain, atomic structure at nanoscale. It provides direct visualization of strainmagnetic coupling in ferromagnetic materials, opening avenues for studying nanomagnetism.

Interference gating (iGate) has emerged as a groundbreaking technique for ultrafast time-resolved electron holography in transmission electron microscopy, delivering nanometer spatial and nanosecond temporal resolution with minimal technological overhead. This study employs iGate to dynamically observe the local projected electric potential within the space-charge region of a contacted transmission electron microscopy (TEM) lamella manufactured from a silicon diode during switching between unbiased and reverse-biased conditions, achieving a temporal resolution of 25 ns at a repetition rate of 3 MHz. By synchronizing the holographic acquisition with the applied voltage, this approach enables the direct visualization of time-dependent potential distributions with high precision. Complementary static and dynamic experiments reveal a remarkable correspondence between modeled and measured projected potentials, validating the method’s robustness. The observed dynamic phase progressions resolve and allow one to differentiate between localized switching dynamics and preparation-induced effects, such as charge recombination near the sample edges. These results establish iGate as a transformative tool for operando investigations of semiconductor devices, paving the way for advancing the nanoscale imaging of high-speed electronic processes.

The all-optical control of magnetization at room temperature broadens the scope of applications of spin degrees-of-freedom in data storage, spintronics, and quantum computing. Topological magnetic spin structures, such as skyrmions, are of particular interest due to their particle-like properties, small size and inherent stability. Controlling skyrmion states without strong magnetic fields or large current densities would create new possibilities for their application. In this work, we utilize femtosecond optical pulses to alter the helicity of the spin configuration in dipolar skyrmions formed in the kagome magnet Fe_3Sn_2 in the absence of an external magnetic field and at room temperature. In situ Lorentz transmission electron microscopy is used to visualize the stochastic, light-induced switching process of chiral Néel caps, while the internal Bloch component of the dipolar skyrmions remain unchanged. In addition to this switching process, we observe the interconversion between type I skyrmionic and type II bubble configurations depending on the external magnetic field and illumination conditions. To corroborate the spin states and the light-induced magnetization dynamics, micromagnetic modelling and simulations of the resulting electron phase shift maps are conducted to elucidate the spin rearrangement induced by individual femtosecond optical pulses.

During the past few years, serial electron crystallography (serial electron diffraction) has been gaining attention for the structure determination of crystalline compounds that are sensitive to irradiation by an electron beam. By recording a single electron diffraction pattern per crystal, indexing thousands to tens of thousands of such patterns and merging the reflection intensities of the successfully indexed patterns, one can retrieve crystal structure models with strongly mitigated beam damage contributions. However, one of the technique's bottlenecks is the need to obtain so many well indexed diffraction patterns, which leads to the collection of raw diffraction data in an automated way that usually yields low indexing rates. This work demonstrates how to overcome this limitation by performing the serial crystallography experiment following a semi-automated routine with a precessed electron beam (serial precession electron diffraction). The precession movement increases the number of reflections present in the diffraction patterns, and dynamical effects related to specific orientations of the crystals with respect to the electron beam are greatly minimized. This leads to more uniform reflection intensities across the serial data set, and a smaller number of patterns are required to merge the reflection intensities for good statistics. Furthermore, structure refinements based on the dynamical diffraction theory become possible due to the diffraction volume integration of beam precession, providing a novel approach for more accurate structure models. In this context, the use of beam precession is presented as an advantageous tool for serial electron crystallography, as it enables reliable crystal structure analysis with a lower amount of diffraction data.

A hybrid chiral skyrmion tube is a well-known example of a 3D topological spin texture, exhibiting an intriguing chirality transition along the thickness direction. This transition progresses from left-handed to right-handed Néel-type chirality, passing through a Bloch-type intermediate state. Such an exotic spin configuration potentially exhibits distinctly different dynamics from that of the common skyrmion tube that exhibits a homogeneous chirality; yet these dynamics have not been ascertained so far. Here we reveal the distinct features of current-induced dynamics that result from the hybrid chiral skyrmion tube structure in synthetic antiferromagnetic (SyAFM) multilayers. Strikingly, the SyAFM hybrid chiral skyrmion tubes exhibit a non-reciprocal skyrmion Hall effect in the flow regime. The non-reciprocity can even be tuned by the degree of magnetic compensation in the SyAFM systems. Our theoretical modeling qualitatively corroborates that the non-reciprocity stems from the dynamic oscillation of skyrmion helicity during its current-induced motion. The findings highlight the critical role of the internal degrees of freedom of these complex skyrmion tubes for their current-induced dynamics.

Mn-rich layered oxides (MRLOs) are promising low-cost cathode materials for sustainable sodium-ion batteries (SIBs). However, the low Mn4+/Mn3+ redox potential limits their energy densities, and the Jahn-Teller distortion that occurs surrounding Mn3+ at low voltages destabilizes the structure. Additionally, complex ordered structures inherently present in MRLOs hinder Na+ migration. In this study, new types of cation ordering structures are discovered in common MRLOs. By regulating oxygen vacancy formation, the transition from short-range to long-range cation ordering is disrupted, effectively mitigating cooperative Jahn-Teller distortion and achieving a 95.3% capacity retention over 1 000 cycles at 8 C. The maximum entropy method (MEM) analysis is performed based on neutron diffraction data, which visualizes significantly optimized Na+ diffusion pathways in long-range disordered cathode with enhanced Na+ diffusion kinetics. Furthermore, the formation of oxygen vacancy elevates the Mn4+/Mn3+ redox potential, resulting in a competitive energy density of 626 Wh kg-1 within 1.5-4.5 V in a half-cell configuration. This work offers a multiscale approach to precise elucidation of the cathode crystal structure and provides a feasible pathway to optimize sodium-ion cathodes by disrupting long-range cation ordering, ultimately facilitating substantial improvements in electrochemical performance.

Conductive ceramics currently play a vital role in human life. In practical applications, most conductive ceramics are polycrystalline, and their overall conductivity (sigma total) is influenced by both bulk and grain boundary resistances (Rbulk and Rgb, respectively). While Rbulk is mainly of academic interest, Rgb often determines the quality of a conductive ceramic component. Currently, studies discussing the influence of specific methods on grain boundary resistances are typically related to individual ceramics. In this study, it is discovered that the addition of 0.5-3 mol% nominal LaNbO4 significantly reduces the Rgb of several well-known conductive ceramics, such as rhombohedral NaSICON-type Na+-ion-conducting Na3.4Zr2Si2.4P0.6O12 and Li+-ion conducting Li1.5Al0.5Ti1.5P3O12, Li+-ion-conducting tetragonal perovskite Li0.34La0.56TiO3, oxygen-ion-conducting cubic fluorite 8 mol% Y2O3 stabilized ZrO2, and electron-conducting perovskite SrTiO3 (sintered in a reducing atmosphere). In particular, for NZSP and LATP, the enhanced sigma total reaches 9.3 x 10-3 S cm-1 and 2.1 x 10-3 S cm-1 at 25 degrees C, surpassing previously published results. Detailed investigations reveal that the microstructure of the grain boundaries in all the ceramics undergoes significant improvements. The findings elevate the importance of research on grain boundaries, inspiring the development of conductive ceramics with higher sigma total for superior applications.

Marginally twisted WS2 bilayers undergo lattice reconstructions, but it is unclear if the distortion is equally distributed or confined to specific sublayers. Here, we use in situ combined noncontact atomic force microscopy with scanning tunneling spectroscopy to tune the probing depth to extract electronic and atomic lattice information for each sublayer separately. We find a lattice reconstruction unexpectedly confined to the WS2 layer in contact with graphite only, governed by transition metal dichalcogenide-substrate interactions, leading to a peculiar type of a ferroelectric domain wall.

Magnetism originates from the spin and orbital angular momenta of electrons and their coupling. These interactions occur at subatomic scales and a comprehensive understanding of such phenomena relies on characterization techniques capable of probing the spin and orbital moments at atomic resolution. Although electron energy loss magnetic chiral dichroism has previously enabled the detection of magnetic moments at atomic scales, it was limited to a chromatic-aberration-corrected transmission electron microscope. Although possible, the detection of atomic-scale electron energy loss magnetic chiral dichroism in a scanning transmission electron microscope remains elusive due to challenges associated with convergent beam setups. Here we demonstrate the detection of atomic-scale electron energy loss magnetic chiral dichroism signals in a probe-corrected scanning transmission electron microscope. We not only determine the orbital-to-spin moments ratio for individual atomic planes of an iron crystal but also reveal its local variations at subatomic scales. These findings open the possibility of resolving magnetism down to the orbital level in future studies.

Nanoscale superconducting quantum interference devices (nanoSQUIDs) with nanobridge Josephson junctions (nJJs) were prepared on SiN membranes for experiments with transmission electron microscope (TEM) at temperatures below 10 K. As thin-film materials for the nanobridges, metals Ti and Nb were combined into 3-layer heterostructures for adjusting superconducting parameters of the nJJs through the proximity effect. This allowed to reduce spread of parameters in ultrathin superconducting films and to adjust operating temperature of nJJs to the optimum operating temperature of the commercial TEM sample holders cooled using liquid helium. Electron beam lithography and high selectivity reactive ion etching with pure SF6 gas were used to pattern nJJs with down to 10 nm width that is comparable to coherence length in thin films of Nb. Measurements revealed non-hysteretic I(V) characteristics of the nJJs and nanoSQUIDs. The paper is mainly devoted to the development of nanoSQUIDs for possible applications in TEM. Towards realization of hybrid superconductor-ferromagnetic nanostructures for further experiments in TEM, Permalloy triangles with spatial resolution down to similar to 100 nm were prepared on similar SiN membranes and studied by Lorentz TEM method. These technologies are promising for the fabrication of superconducting electronics based on nJJs for operation inside a TEM.

We investigate how data acquisition rate affects the decoherence of diffraction speckles in fluctuation electron microscopy (FEM) experiments on amorphous silicon at 80 kV. Surprisingly, reducing acquisition time from 256 ms to 1 ms does not significantly enhance the intensity variance peaks related to medium-range order. This suggests that decoherence processes operate at timescales faster than 1 ms. At the highest acquisition rates, noise complicates the variance background estimation. A significant source of non-Poisson noise is the spread of electron signals across adjacent detector pixels. We mostly restore the discrete pulse counting needed to mitigate Poisson noise by rounding pixel intensity to the nearest integer-electron value. However, a residual negative-variance offset grows as the acquisition rate increases. Efficient electron pulse counting in detectors is crucial for processing Poisson noise in FEM, especially with weak signals.

The all-optical control of magnetisation at room temperature broadens the scope of applications of spin degrees-of-freedom in data storage, spintronics, and quantum computing. Topological magnetic spin structures, such as skyrmions, are of particular interest due to their particle-like properties, small size and inherent stability. Controlling skyrmion states without strong magnetic fields or large current densities would create new possibilities for their application. In this work, we utilize femtosecond optical pulses to alter the helicity of the spin configuration in dipolar skyrmions formed in the kagome magnet Fe3Sn2 in the absence of an external magnetic field and at room temperature. In situ Lorentz transmission electron microscopy is used to visualise the light-induced stochastic switching process of chiral Néel caps, while the internal Bloch component of the dipolar skyrmions remains unchanged. In addition to this switching process, we observe the interconversion between type I skyrmionic and type II bubble configurations depending on the external magnetic field and illumination conditions. To corroborate the spin states and the light-induced magnetisation dynamics, micromagnetic modelling and simulations of the resulting electron phase shift maps are conducted to elucidate the spin rearrangement induced by individual femtosecond optical pulses. The all-optical control of magnetization at room temperature expands the potential of spin-based technologies in data storage and quantum computing. Here, the authors use femtosecond optical pulses to manipulate skyrmion states in Fe₃Sn₂ without external magnetic fields, revealing light-induced switching and interconversion processes, with implications for advanced spintronic applications.

Collecting and averaging large datasets is a common practice in transmission electron microscopy to improve the signal-to-noise ratio. Averaging data in off-axis electron holography requires automated tools capable of correcting both the drift of the interference fringes and the drift of the specimen. This can be achieved either off-line, by post-processing hologram series, or on-line, through real-time microscope control. For on-line correction, a previously suggested method involves independently adjusting the position of the intereference fringes and the sample by controlling the beam tilt coils and the stage during hologram acquisition. In this study, we have implemented this on-line correction method in a Thermo Fisher Scientific Titan transmission electron microscope. The microscope is equipped with a piezo-enhanced CompuStage for positioning the sample with high precision. However, the control of the piezo stage via direct scripting is not supported. We first describe a workaround to enable automated sample position correction. We then demonstrate the benefits of live, program-controlled acquisitions for serial experiments in medium resolution off-axis electron holography. Application examples include the automatic acquisition of an object series such as a transistor array and an in-situ temperature series of magnetic skyrmions.