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Multiferroic materials are of interest because they allow control of their magnetic properties through electric fields. However, room-temperature magnetoelectrics often show antiferromagnetic order, reducing the effects of such coupling. A novel approach demonstrates switchable electric field control over a local magnetic field through the indirect route of exchange bias.

Scaling effects on ferroelectric domains could impact applications for next-generation miniaturized devices. Here brownmillerite oxides are shown to demonstrate ferroelectric domains with widths down to the sub-unit-cell level.

Mirror twin boundaries in monolayer MoS₂—line defects with reflection-mirroring symmetry—are one-dimensionally metallic. In this work, the authors fabricate these mirror twin boundary networks by epitaxity and incorporate them into ultrascaled 2D transistor circuits as gate electrodes.

We visualize an electric-field-induced collective propagation of oxygen vacancies spontaneously contained in Ca-substituted BiFeO₃ films, using the fact that the oxygen-rich and poor regions have different color contrasts and thus they are optically distinguishable forming a sharp boundary. We quantitatively determine the drift velocity to be of the order of 100 μm s⁻¹ with an activation barrier of 0.79 eV indicating a significantly large ionic mobility 2 × 10⁻⁶ cm² s⁻¹ V⁻¹ at a remarkably low temperature of 390 °C. Furthermore, U-shaped propagation and turbulence under backward electric field provide insights into fluidic defects in crystalline solids.

An electret can be created in a complex transition metal oxide LaMnO₃ by tip-induced electric fields with a considerable surface height change via solid-state electrochemical amorphization. The surface charge density of the formed electret area reaches ~400 nC cm⁻² and persists without significant charge reduction for more than a year. Our finding opens a new horizon for multifunctional transition metal oxides by providing an electric counterpart to permanent magnets.

Phase transition points can be used to reduce the ionic migration activation energy. Here, the authors find a lowered activation energy associated with oxygen transport at a compositional phase transition point in Ca-doped bismuth ferrite films.

The control of magnetism by electric field is an important goal for future development of low-power spintronics. Here, the authors demonstrate voltage control of magnetism in van der Waals ferromagnetic/ferroelectric heterostructure devices via the strain-mediated magnetoelectric effect.

Magnetoelectric materials combine ferroelectric and magnetic properties through a coupling of the spin and lattice degrees of freedom. Here, magnetoelectric bismuth ferrite is found to simultaneously undergo both a magnetic and a ferroelectric transition at the same temperature.

Observation of a strain-gradient-induced piezoresponse at domain walls remains a challenge. Here, the authors find the piezoelectric response to be enhanced in the ferroelastic domain walls of centrosymmetric tungsten trioxide thin films due to a large strain gradient over a wide width of the wall.

The triple point is a well-known feature on pressure–temperature phase diagrams. A multiferroic triple point is now reported for La-doped BiFeO₃; La concentration and temperature are the phase variables and the phases display different spin (dis)order.

The photocurrent in polymorphic phase areas of BiFeO₃ is enhanced by a factor of 100 due to interfacial strain gradients across the different structural phases.

The generation of charge-neutral anti-Frenkel defects in a complex transition metal oxide provides a useful pathway for controlling electronic conductivity while minimizing the impact on existing functions.

Exploring topological textures in ferroelectrics facilitates the understanding and application of topological features in matter. Here the authors demonstrate the strain field induced evolution of topological vortices in nanoplatelets of rhombohedral phase BiFeO3 using the angle-resolved piezoresponse force microscopy.

Scanning a La-doped BiFeO₃ epitaxial thin film with a biased AFM tip, we produce straight stripe one-dimensional nanostructures in which two competing polymorphic ferroelectric phases appear alternately at the interval of ∼100 nm showing the enhancement of electronic conduction at the phase boundaries. We can create, switch and erase the eight-variant stripe nanostructures in a reversible and deterministic way by controlling the tip scanning direction and tip biased voltage. The findings provide a new pathway into one-dimensional nanostructures and versatile patterns of ferroelectric domains and interfaces.

We demonstrate a single-domain photovoltaic switch based on lateral BiFeO₃ channels, in which such photovoltaic switching is achieved by a coherent single-domain reversal with a short electrical pulse. We then provide visual evidence for such operations with a series of spatially and spectrally resolved short circuit photocurrent images. Specifically, it reveals that the sequential photovoltaic current images directly reflect the remanent polarization states of a single-domain channel. We also verify that, in multidomain channels, the diffusive switching characteristics is determined not only by the internal polarization vector within the domain but also by oxygen vacancy migration at the domain walls.

Strong correlation between the local strain state and the electronic properties at orthorhombic–rhombohedral (O-R) phase boundaries in mixed-phase BFO thin films leads to electronic conductivity at these boundaries. This rather unusual electrical feature might find applications in nanotechnology.