Research articles

The control and manipulation of the magnetization of thin metallic films by means of an electric current is a promising strategy for ensuring that potential spintronic applications are energy efficient. It is now shown that large changes in the current-induced magnetic field can arise as a result of varying the thickness of the Ta layer in Ta|CoFeB|MgO heterostructures.

Because it is an intrinsically slow technique, scanning tunnelling microscopy is not usually useful for studying the dynamics of particles on a surface. This issue is now solved by using scanning noise microscopy, which yields a complete characterization of copper phthalocyanine molecules on Cu(111), ranging from the dynamical processes to the underlying electronic structure at the single-molecule level.

Emulating the spiking phenomena associated with neural activity in technological devices offers the promise of drastically improving their efficiency and scale. The fabrication of a neuristor that consists of nanoscale Mott memristors provides a step towards making such devices practical for integrated circuit applications.

Graphene has attracted considerable interest for future electronics, but the absence of a bandgap limits its direct applicability in transistors and logic devices. It is now shown that vertical integration with MoS₂ and other layered materials enables the fabrication of vertical field-effect transistors with large on/off ratios and high current densities as well as complementary inverters with larger-than-unity voltage gain.

Non-trivial topological phases can allow for one-way spin-polarized transport along the interfaces of topological insulators but they are relatively uncommon in the condensed state of matter. By arranging judiciously designed metamaterials into two-dimensional superlattices, a photonic topological insulator has now been demonstrated theoretically, enabling unidirectional spin-polarized photon propagation without the application of external magnetic fields or breaking of time-reversal symmetry.

The standard picture of organic photovoltaics predicts that excitons, which are created under light irradiation, thermalize before dissociation into free electrons and holes. Experimental results and calculations on a low-bandgap polymer–fullerene blend now illustrate the dynamics of hot charge-transfer states and their contribution to charge generation in bulk heterojunctions.

Gathering information on the evolution of small cracks in ceramic matrix composites used in hostile environments such as in gas turbines and hypersonic flights has been a challenge. It is now shown that sequences of microcrack damage in ceramic composites under load at temperatures up to 1,750 °C can be fully resolved with the use of in situ synchrotron X-ray computed microtomography.

Photocurrent generation in organic solar cells relies on the dissociation of excitons into free electrons and holes at donor/acceptor heterointerfaces. Femtosecond spectroscopy and non-adiabatic simulations on the phthalocyanine–fullerene model system now reveal the relaxation dynamics of hot charge-transfer excitons in this process.

Solid-state spin qubits offer promise as building blocks for quantum computers. Now, efficient quantum control is demonstrated over hybrid nuclear–electronic qubits in bismuth-doped silicon, as a consequence of the strong hyperfine interactions in this system.

Rechargeable metal–air batteries are considered particularly attractive due to their potential high-energy densities and simplicity of the underlying cell reaction. A room-temperature sodium–oxygen cell with an ether-based electrolyte demonstrates enhanced current densities using pure carbon cathodes without an added catalyst.

The dynamical properties of single-chain magnets are difficult to control experimentally. The demonstration of a scheme for switching individual spins optically now allows for the study and manipulation of dynamical processes in magnetic nanowires with comparative ease.

The appealing electronic properties of the monolayer semiconductor molybdenum disulphide make it a candidate material for electronic devices. The observation of tightly bound trions in this system—which have no analogue in conventional semiconductors—opens up possibilities for controlling these quasiparticles in future optoelectronic applications.

A critical component for chip-scale integrated photonics would be a non-reciprocal optical waveguide allowing light to travel in only one direction while reflecting it in the opposite one. Inspired by concepts of parity-time-symmetric quantum theories, a periodically modulated dielectric waveguide displaying unidirectional reflection is now demonstrated, reflecting light at telecom frequencies in only one direction.

Determining crystal structures from diffraction experiments can be labour intensive and prone to errors. A hybrid approach combining experimental diffraction data, statistical symmetry information and first principles-based algorithmic optimization is now proposed to automatically solve crystal structures.

The exterior surface of cell membranes in eukaryotes is surrounded by glycans. It is now found that the spatial configuration of these polysaccharide molecules controls the phase behaviour of multiphase lipid membranes—either by stabilizing ordered lipid domains or by suppressing macroscopic lipid phase separation—and that this glycan-induced patterning is thermally reversible.

The layered iron pnictide superconductors are known for their unconventional electronic properties and high critical temperatures. Now, SmFeAs(O,F) is shown to undergo a transition from pinned Abrikosov-like to mobile Josephson-like vortices as the system is cooled below its critical temperature.

The poor thermal conductance of interfaces is a significant bottleneck to the integration of nanoscale devices in a range of applications. Now, the thermal conductance at metal/dielectric heterointerfaces is significantly enhanced by the introduction of an organic nanomolecular monolayer.

The properties of the insulating ground state from which the superconductivity of copper oxide materials emerges with chemical doping are a topic of extensive research. The observation that superconducting fluctuations are quenched by charge order at low temperatures now provides valuable information on the mechanism for the superconducting to insulator transition.

Nanoplasmonic structures that can detect trace analytes via surface-enhanced Raman spectroscopy typically require sophisticated nanofabrication techniques. Self-assembly of gold nanoparticles into close-packed arrays at liquid/liquid and liquid/air interfaces is now used for the detection of multi-analytes from aqueous, organic or air phases.

Metamaterials offer a unique potential to guide the propagation of light. However, existing designs of devices such as invisibility cloaks require a restrictive range of materials parameters for their realization. A new approach to cloak devices now lifts such restrictions allowing for a greater flexibility in device design.