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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.

The authors demonstrate strain-induced morphotropic phase boundary-like nanodomains in lead-free NaNbO₃ thin films, enabling multi-state switching and large enhancements in dielectric susceptibility and tunability over a broad frequency range.

In a material system, a distortion constitutes a change from one stable state to another via a pathway built from a combination of atomic trajectories. Here, the authors present a distortion reversal antisymmetry operation which fully describes the symmetry of such pathways.

The symmetries of crystals are an important factor in the understanding of their properties. The discovery of a new symmetry type, rotation-reversal symmetry, may lead to the discovery of new rotation-based phenomena, for example in multiferroic materials.

Proximity ferroelectricity is reported in wurtzite heterostructures, which enables polarization reversal in wurtzites without the chemical or structural disorder that accompanies elemental substitution.

Sen et al. report the stacking of a perovskite incipient ferroelectric nanomembrane with atomically thin 2D material for a back-end-of-line compatible ferroelectric-like field effect transistors, functioning as a cryogenic memory at 15 K and as an inference engine at room temperature.

New findings suggest that the mechanical stretching of layered crystals can transform them from a polar to a nonpolar state. This could spur the design of multifunctional materials controlled by an electric field.

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.

Fabricating doped semiconductor layers and p–n junctions inside silica optical fibres allows the realization of a new breed of in-fibre optoelectronic devices, such as photodetectors with gigahertz bandwidths.

BaTiO₃ can remain ferroelectric at temperatures up to at least 330 °C when it is strained by self-assembled nanoscale columns of SmO.

Manipulating the electronic properties of topological semimetals is a central goal of modern condensed matter physics research. Here, the authors demonstrate how a high-entropy engineering approach allows for the tuning of the crystal structure and the electronic states in a Dirac semimetal.

An electron glass state usually occurs in disordered insulating systems. Here the authors report evidence of glassy dynamics of conduction electrons in an electron-doped quantum paraelectric material KTaO₃, in the good metal regime, where quantum fluctuations play an important role.

Electronic bandwidth modulation by static pressure has been explored in several material families. Wang et al. use temperature-dependent Raman spectroscopy and density functional theory to reveal phonon-driven modulation of electronic pseudogap and density wave fluctuations in a ruthenate Ca₃Ru₂O₇.

The nonlinear Hall effect (NLHE) results in a second-harmonic transverse voltage in response to alternating longitudinal current in zero magnetic field and has so far only been observed at low temperatures in bulk materials. Here, the authors observe bulk NLHE at room temperature in the Dirac material BaMnSb₂, which will provide a large photocurrent for applications in THz detection.

Materials with spatially modulated nonlinear optical properties are used for quasi-phase matching. Here, Yanet al. exploit the nonlinearity of intermolecular charge transfer states together with oblique-angle deposition to achieve nanoscale modulation of the second-order susceptibility.

Competing phases in layered complex oxides are believed to be relevant for emergent phenomena, which still await to be witnessed. Here, Stone et al. report direct atomic-scale imaging of a multitude of polar phases in Ruddlesden-Popper oxide thin films, exhibiting diverse phenomena in a single structure.

Tunable coupling between magnetism and the lattice is important for on-demand manipulation of magnetic phases. Here, the authors demonstrate that lattice vibrations can coherently modulate the interlayer magnetic exchange coupling in the magnetic topological insulator MnBi₂Te₄.

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.

Materials that combine metallic behaviour with stable electric polarization are scarce despite being proposed in the 1960s. Here the authors engineer a perovskite heterostructure where 2D polar metallic behavior coexists with built-in electric polarization from the displacement of B-site titanium cations.

Multiferroic materials exhibiting ferromagnetism (FM) and ferroeletricity (FE) at room temperature (RT) are promising for applications. Here, the authors demonstrate by inducing strain in SmMnO3 via introducing vertically aligned nanocomposites that exchange coupling can be modified tuning the system from anti-FM to FM and simultaneously inducing FE at RT.

Electronic many-body effects are used to control the electron effective mass, and thus the plasma energy and electrical conductivity, of thin films of the correlated metals SrVO₃ and CaVO₃, making them good candidates as transparent conductors.

Oxynitrides are garnering interest because of their variety of novel properties, but their synthesis has typically involved highly reducing conditions that put significant constraints on their composition, structure and properties. Now, the lability of H⁻ in perovskite oxyhydride BaTiO_3−xH_x has enabled H^–/N^3– exchange at a lower temperature, yielding a ferroelectric oxynitride BaTiO_3−xN_2x/3.

Double corundum-related polar magnets are promising for multiferroic and magnetoelectric applications in spintronics, but are limited by the challenging design and synthesis. Here the authors report the synthesis of Mn₂MnWO₆ as well as its appealing multiferroic and magnetoelectric properties.

Morphotropic phase boundaries, which separate two competing phases of different chemical composition, are the crucial ingredient for lead-based piezoelectrics. Here, the authors show that similar enhanced properties and analogous thermotropic phase boundaries can occur in simple, lead-free ferroelectrics.

In complex oxides, oxygen octahedra are major structural motifs and their tilts sensitively determine the material’s physical properties. Exploiting Coherent Bragg Rod Analysis enables 3D mapping of complex tilt patterns and reveals the means to control polarization through them in CaTiO₃ thin films.

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.

A new family of tunable microwave dielectrics with unparalleled performance at frequencies up to 125 GHz at room temperature has been created, using dimensionality to add and control a local ferroelectric instability in a system with exceptionally low dielectric loss.

Kagome materials have recently attracted significant attention due to their ability to house both topological and magnetic phases. Here, the authors report a high-entropy Kagome magnet that exhibits an anomalous Hall effect, indicating the nontrivial topological properties for the high entropy phase remain.

Multiferroics that are both ferroelectric and ferromagnetic are highly desirable for technological applications but extremely rare. Here, signatures of a ferroelectric phase transition, supported by theoretical calculations, are observed in ferromagnetic EuO under a large epitaxial strain of 6.4%.

Optically transparent electrodes with high electrical conductance are essential for the implementation of optoelectronics, but current technology performs poorly in the ultraviolet regime. Here, SrNbO₃ is proposed as an alternative material due to its high figure of merit in the ultraviolet range.