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In the standard model of particle physics the permanent electric dipole moment of particles is zero, although competing theories suggest it must exist to explain the asymmetry of matter and antimatter in the Universe. The design and synthesis of a new multiferroic material may now enable us to search for the electric dipole moment of electrons with unprecedented precision.

Evolution of improper ferroelectricity within the confinement of ultrathin films is essential for their successful implementation in nanoscale applications. Here, the authors show thickness dependence of the improper polarization originating from the strong modification of the primary order at epitaxial interfaces.

The control of magnetization by an electric field can offer new magnetic data devices. Here, controlling magnetic phases in FeRh, the authors achieve a large electroresistance response in FeRh/PMN-PT heterostructures by applying an electric field, which could be used for non-volatile memory applications.

Domain walls may be important in future electronic devices, given their small size as well as the fact that their location can be controlled. In the case of insulating multiferroic oxides, domain walls are now discovered to be electrically conductive, suggesting their possible use in logic and memory applications.

With only a few known useful room-temperature multiferroics, other ways of achieving materials showing magnetism as well as electrical polarization are sought. The discovery that the ferroelectric BaTiO₃ also shows magnetism at room temperature at the interface with iron or cobalt marks a new approach to achieving multiferroic properties.

Magnetic insulators often display antiferromagnetic ordering owing to implications from the Pauli exclusion principle. Here, the authors predict ferromagnetism on the basis of intra-site Hund's rules in ferroelectric titanate superlattices showing charge and Jahn–Teller induced orbital orderings.

In h-RMnO₃, the linear magnetoelectric effect is symmetry forbidden. Here, the authors show a pronounced magnetoelectric coupling driven by superexchange interaction giving rise to types of topological defects like magnetoelectric domain walls and vortex-like singularities.

Oxide materials show a versatile range of phenomena that in many cases can be controlled by growing thin films of oxides next to each other. The observation now that electrical conductance of domain walls in a ferroelectric can be tuned simply through the domain-wall orientation offers a flexible way of controlling functionality in complex oxides.

Electric-field control of the conductivity of domain walls in ferroelectric ErMnO₃ has been demonstrated. Reversible switching between conducting and insulating states is attributed to an inversion layer, which provides a channel for conduction.

Polarons are quasiparticles formed when an electron strongly couples to the lattice vibrations, or phonons, in a crystalline material. Here, the authors use soft-X-ray angle-resolved photoelectron spectroscopy to identify signatures of metal polarons at the interface between two oxide materials.

Magnetoelectric multiferroics, where magnetic properties are manipulated by electric field and vice versa, could lead to improved electronic devices. Here, advances in materials, characterisation and modelling, and usage in applications are reviewed.

Femtosecond X-ray diffraction and ab initio density functional theory calculations are used to determine the crystal structure of YBa₂Cu₃O_6.5 undergoing optically driven, nonlinear lattice excitation above the transition temperature of 52 kelvin, under which conditions the electronic structure of the material changes in such a way as to favour superconductivity.