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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.

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.

Whilst superlattices containing thin films of 5d transition metal oxides are expected to yield strong interfacial coupling, only weak effects have been observed. Here, the authors report strong coupling between 3d SrMnO₃ and 5d SrIrO₃due to the interplay of strong Coulomb and spin orbit interactions.

Interesting proximity effects can occur at the interface of superconducting and ferromagnetic oxides, but they are poorly understood. Here, the authors use scanning tunnelling and electron microscopy techniques to investigate such an interface, showing that the charge transfer has an upper limit of 1 nm.

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.

The polar chiral texture of the vortex or skyrmion structure in ferroelectric oxide PbTiO₃/SrTiO₃ superlattice attracts attention. Here, the authors report a theoretical framework to probe emergent chirality of electrical polarization textures.

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.

Trivalent lanthanides are typically described using an ionic picture that leads to localized magnetic moments. Here authors show that the “textbook” description of lanthanides fails for Pr⁴⁺ ions where the hierarchy of single-ion energy scales can be tailored to explore correlated phenomena in quantum materials.

Understanding structure–function relationships at oxide-solution interfaces is highly desirable. Here, Chang et al.study the oxygen evolution reaction on strontium ruthenate single-crystal films in alkaline environments, and establish relationships between conductivity, stability and activity of the catalysts.

Electrical readout of the state of an antiferromagnet is an important goal for spintronic applications. Now, detection of the electrical voltage created by a thermal gradient in a canted antiferromagnet suggests a route for achieving this goal.

In the standard Si transistor gate stack, replacing conventional dielectric HfO₂ with an ultrathin ferroelectric–antiferroelectric HfO₂–ZrO₂ heterostructure exhibiting the negative capacitance effect demonstrates ultrahigh capacitance without degradation in leakage and mobility, promising for ferroelectric integration into advanced logic technology.

A dynamical study shows that vortices of electrical polarization have higher frequencies and smaller size than their magnetic counterparts, properties that are promising for electric-field-driven data processing.

Na₃V₂(PO₄)₂F₃ is a promising cathode material for Na-ion batteries, although its third sodium is usually not accessible electrochemically. Here the authors realize a disordered tetragonal NVPF phase, which can reversibly uptake 3 Na-ions and enables improved energy density for the NVPF/C full cell.

The desirable functional properties of complex oxide materials are often influenced by the presence of oxygen defects and epitaxial strain. Meyer et al. demonstrate the role of oxygen defect kinetics in the strain control of the superconducting transition temperature of LSCO.

Unusual electronic behavior can emerge in complex oxides due to strong coupling between charge, magnetic and lattice degrees of freedom. Zhu et al. observe separation of electronic and lattice equilibration times in La_1/3Sr_2/3FeO₃ as magnetic interactions make the recovery of charge order much slower than lattice relaxation.

The behaviour of strongly correlated nickelates is well studied in bulk but the corresponding strained thin films are largely unexplored. Here, the authors study strained NdNiO₃thin films with various degrees of strain and, in addition to a metal-to-insulator transition, find quantum critical behaviour.

Low-temperature redox reactions in solids resulting in no thermomechanical degradation can be used to enhance the performance and lifetime of energy devices. Rapid and reversible redox activity has now been demonstrated at temperatures as low as 200 °C in both epitaxially stabilized oxygen-vacancy-ordered SrCoO_2.5 and thermodynamically unfavourable perovskite SrCoO_3−δ single-crystalline thin films.

Understanding lithium dynamics in solid-state electrolytes used for Li-ion batteries can be challenging. Using nonlinear extreme-ultraviolet spectroscopies, a direct spectral signature of surface lithium ions showing a distinct blueshift relative to the bulk absorption spectra is observed in a prototypical solid-state electrolyte.

Application of an electric field changes the transport and optical properties of samarium nickelate submerged in water, making it a suitable passive sensor of weak electric fields in salt water.

Ferroelectric ferromagnets — materials that are both ferroelectric and ferromagnetic — are of significant technological interest. But they are rare, and those that do exist have weak ferroelectric and ferromagnetic properties. Recently a new way of fabricating such materials was proposed, involving strain from the underlying substrate. This route has now been realized experimentally for EuTiO₃. The work shows that a single experimental parameter, strain, can simultaneously control multiple order parameters.

Coupling a ferromagnetic insulator to a topological insulator induces a robust magnetic state at the interface, resulting from the large spin-orbit interaction and the spin-momentum locking property of Dirac fermions, and leads to an extraordinary enhancement of the magnetic ordering (Curie) temperature.

The metal-insulator transition is well-known phenomenon in condensed-matter physics but the mechanisms driving the insulating state can vary from system to system and so understanding the underlying physics is complex. Here, the authors investigate electronic structure of single crystalline, Ca-doped NdNiO3 using synchrotron measurements and DFT calculations, illuminating the importance of bond disproportionation in the observed properties.