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Atomic point defects formed by irradiation can dramatically alter material properties, but are difficult to probe, limiting understanding of their impact. Here, the authors introduce an x-ray microscopy approach, based on Bragg ptychography, to visualise the distortion caused by these otherwise invisible defects.

The energy loss of ions in plasma is a challenging issue in inertial confinement fusion and many theoretical models exist on ion-stopping power. Here, the authors use laser-generated plasma probed by accelerator-produced ions in experiments to discriminate various ion stopping models near the Bragg peak.

Imaging the antiferromagnetic (AFM) domains facilitates the understanding and design of AFM spintronics but is still challenging. Here the authors show an imaging approach for antiphase domains in AFM Fe₂Mo₃O₈ by resonantly scattered coherent soft X-rays, which is also applicable to collinear antiferromagnets.

Surface-sensitive scanning tunneling microscopy (STM) has previously found a charge density wave (CDW) up to 10 K in the normal state of the heavy-fermion superconductor UTe₂. Here, using resonant elastic X-ray scattering (REXS) above the superconducting transition, the authors find no evidence for a bulk CDW, suggesting the normal state CDW observed by STM is a surface effect.

Femtosecond photoexcitation drives a coherent twist–untwist motion of the moiré superlattice in 2° and 57° twisted WSe₂/MoSe₂ heterobilayers.

Ultrafast electron diffraction is used here to reveal in nickel an almost instantaneous, long-lasting population of anisotropic phonons with angular momentum.

Coherent diffraction experiments and molecular dynamics enable the study of atomic contraction in gold nanocrystals. They reveal a surface-orientation dependence of the atomic bond contraction—remarkably different from the situation in bulk.

Phonon lasers are the acoustic equivalent to optical lasers. Here Maryam and colleagues study the dynamics of semiconductor phonon lasers operating in the terahertz frequency regime, and show that these dynamics are similar to that of comparable optical lasers.

Microelectromechanical systems (MEMS) are essential in a wide range of photonics applications but have not been demonstrated for X-ray optics. Here, Mukhopadhyay et al.use single-crystal silicon to demonstrate a MEMS system that can preserve and manipulate the spatial, temporal and spectral correlations of the X-rays.

Optimizing the crystallization of the active materials in organic solar cells is challenging. Fu et al. use an acenaphthene additive to induce a two-step crystallization of the non-fullerene acceptor, achieving a certified 20.5% power conversion efficiency.

The photoinduced hidden metallic state in 1T-TaS₂ has so far been stabilized only at cryogenic temperatures. Now it is shown that accessing an additional mixed-phase long-lived metastable state can stabilize the hidden phase at higher temperatures.

Researchers describe a mechanism capable of compressing fast and intense X-ray pulses through the rapid loss of crystalline periodicity. It is hoped that this concept, combined with X-ray free-electron laser technology, will allow scientists to obtain structural information at atomic resolutions.

Magnetic symmetry is a vital factor to determine exotic topological phases. Here, Riberolles et al. demonstrate a helical antiferromagnetic order in EuIn₂As₂ which makes it a magnetic topological-crystalline axion insulator.

Some surveys of intelligence have suggested that the mean IQ is rising; others, that it is decreasing alarmingly. The explanation seems to be that the educational level of the populations has changed.

Warm dense matter (WDM), which falls in the category between plasmas and condensed matter, is expected to exist in planetary interiors. Now, researchers use an X-ray laser to observe the transition to WDM.

Unlike the other iron-based superconductors, the parent compounds of the alkaline iron selenide superconductors are insulators. Dai and colleagues examine the spin-wave excitations in these materials and uncover evidence for a common magnetic origin for all iron-based superconductors.

Polar skyrmions are nanoscale topological structures of electric polarizations. Their collective modes, dubbed as “skyrons”, are discovered by the terahertz-field-excitation, femtosecond x-ray diffraction measurements and advanced modeling.

A transverse Peierls transition can occur when transverse acoustic phonons couple with conducting p-orbital electrons. Here, the authors observe an incommensurate transverse Peierls transition and signatures of a chiral charge density wave in EuAl₄.

The hunt for a quantum spin liquid has involved many different material families and models. Now, Zn-barlowite has been found to have similar behaviour to another candidate material, herbertsmithite, hinting there may be universal physical behaviour.

Lasing in a hard-X-ray free-electron laser is typically seeded from noise due to the self-amplification of spontaneous emission, which limits temporal coherence and spectral characteristics. Researchers now demonstrate self-seeding using X-rays from the first half of the magnetic undulator to seed the second half via a diamond-based monochromator at ångström wavelengths.

According to a neutron-scattering study of the structural and magnetic properties of the pnictide CeFeAsO_1−xF_x, the phase diagram of this material shows considerable similarities with the high-T_c cuprate superconductors. These results are an important addition to the effort to find out where superconductivity in these iron–arsenic alloys arises.

A computational approach and software tool, cctbx.xfel, enables the determination of accurate macromolecular structure factors using a relatively small number of serial femtosecond crystallography diffraction snapshots.

Properties of relaxor ferroelectrics are governed by polar nanodomains. Polarization rotation facilitated by these domains investigated by means of epitaxial strain reveals a competition between chemistry-driven disorder and strain-driven order.

Antiferromagnets offer the potential for higher speed and density than ferromagnetic materials for spintronic devices. Here, Reimers et al study the domain structure of CuMnAs, demonstrating the role of defects in stabilizing the location and orientation of antiferromagnetic domain walls.

Superconductivity was discovered in the bismuthate (Ba,K)BiO₃ soon after the discovery of the cuprate high-temperature superconductors. Here, the authors study (Ba,K)BiO₃ using diffuse x-ray scattering and Monte Carlo modeling, finding that nanoscale structural correlations break inversion symmetry locally, while preserving inversion symmetry on average over large length scales.

Understanding transformations of non-equilibrium materials is a key open scientific question. Here the pathway by which different polar supertextures undergo dynamical correlations and collectively transform into a metastable supercrystal state is revealed experimentally and theoretically over seven orders of magnitude timescale.

Transitions between non-degenerate and degenerate plasma are observed in laser-driven implosions of cryogenic capsules at the National Ignition Facility. The observed partially degenerate regime is relevant to the physics of young brown dwarfs.

The understanding of charge density wave (CDW) correlations in cuprate superconductors remains hampered due to the lack of scattering phase information. Here, Chen et al. discover a reproducible CDW domain memory effect upon repeated cycling to temperatures well above the CDW ordering temperature.

Rare earth Nickelates, (RENiO₃) host a bond disproportionation phase transition where oxygen 2p holes form at one of the Ni sites. This process results in a spin-disproportionation state where a singlet state is formed by the spin of the nickel and the spin of the oxygen hole at every other site. Here, Li et al find evidence of this spin-disproportionated state in a rareearth nickelate.

X-ray study of compressed water shows that superionic ice adopts mixed close-packed structures rather than a single phase - a far more complex behaviour than expected, mirroring solid ice’s rich phases and informing planetary interior models.

Engineering the perovskite–electrical contact interface with sodium heptafluorobutyrate reduces interfacial defects and improves charge transport in perovskite solar cells. Functionalized devices deliver a certified power conversion efficiency of 26.96%, which is fully retained after 1,200 h of continuous operation under 1-sun illumination.

Controlling nanoscale colloidal crystallization is not straightforward. Such control is now achieved by leveraging a metastable liquid phase of charged nanocrystals.

The strongly-correlated electron system URu₂Si₂ possesses a hidden-order phase whose order parameter remains unidentified. Here, the authors demonstrate the development of spin-density-wave phases in URu₂Si₂under high magnetic fields, providing a potential in-road to understanding this system.

How local order affects the excellent piezoelectric properties of Pb-based relaxor ferroelectrics is unclear, but neutron diffuse scattering shows that non-relaxor distortions are implicated, indicating the important role of oxygen atoms.

Coherent diffractive imaging during hydriding of palladium nanocrystals reveals that phase nucleation begins after dislocation nucleation at the phase boundary for large particles. The hydrogen-rich phase resembles a spherical cap.

During a photoinduced phase transition, electronic rearrangements are usually faster than lattice ones. Time-resolved measurements now show that the insulator-to-metal transition in a thin-film Mott insulator is preceded by lattice reconfiguration.

This study shows how pressure induces local disorder and partial amorphization in CsPbBr₃, using total X-ray scattering and big-box modeling to reveal reversible structural changes at the atomic scale.

Whilst strong coupling between structure and magnetism is a signature of many of the Fe-based superconductors, no evidence for this has been reported in the normal state of FeSe. Here, the authors demonstrate strong coupling between nematicity and magnetism in FeSe under applied pressure.

Researchers demonstrate one-dimensional photonic crystal lasing with the aid of a cold atom cloud that provides both gain and distributed feedback. Distributed feedback is due to the periodic distribution of the atoms trapped in a one-dimensional lattice enabling Bragg reflection, and parametric gain is provided by four-wave mixing.

In BaFe₂As₂, the lattice couples strongly to the magnetic and electronic degrees of freedom, providing a way to control them. Here, by means of time-resolved X-ray scattering, the authors measure rapid lattice oscillations, which can induce changes in the material’s electronic and magnetic properties.