Research articles

Composites with added carbon nanotubes are known for their improved mechanical strength. Laminates of thin films of aluminium and carbon nanotubes are now used for the fabrication of micromechanical resonators with significantly enhanced mechanical properties.

C₆₀-based solids are the archetypal molecular superconductors, reaching transition temperatures as high as 33 K. Now, Cs₃C₆₀ solids, having a transition temperature of 38 K, have been isolated. Both face-centred-cubic and body-centred-cubic phases were synthesized, and, uniquely among C₆₀ solids, the superconducting phase was found to be body-centred cubic.

Chiral detection using organic sensors has been limited to concentration levels of parts-per-thousand. The use of a thin-film transistor and of semiconducting oligomers with chiral side arms improves differential detection of enantiomers to parts per million.

Efficient light emission combined with high charge-carrier mobility has proven elusive for polymer semiconductors, because high mobility is typically achieved using approaches that quench luminescence. A new strategy, introducing a limited number of more-effective hopping sites between otherwise relatively isolated polymer chains, achieves this aim.

Microporous materials such as zeolites are widely used in separation and catalytic applications. A thermally stable family of zeolites with chiral and achiral structures built from the same layer is now reported.

The large-scale production of high-quality graphene layers is one of the main challenges to be overcome for successful application of this material. Epitaxial growth on ruthenium substrate produces homogeneous domains of single- and double-layer graphene on the scale of several tens of micrometres. The electronic properties of the second layer show great potential for applications.

Inducing and understanding insulator–metal transitions in binary oxide can be challenging. A transition driven chemically by an internal redox reaction is now observed in a non-stoichiometric, amorphous gallium oxide.

We’re all familiar with the annoying problem of trying to peel sticky tape from a surface, only for the detached piece to narrow into a point and break off. Surprisingly, this phenomenon can be put to good use in deriving the mechanical parameters of a wide variety of thin, adhesive films.

The nature of electrostatic charges produced at the surface of insulators by rubbing is the subject of a long-standing discussion. The charges created on polytetrafluoroethylene by rubbing with polymethylmethacrylate are identified here to be electrons rather than ions.

Phase-change materials are of commercial interest for their use in rewritable optical disks and as non-volatile memories, although little is known about the dynamics of the phase transition. The numerical simulation of the entire write-erase cycle therefore provides important clues towards the development of new phase-change materials.

To produce hydrogen by reforming hydrocarbons, efficient catalysts capable of removing carbon monoxide are needed. This can now be achieved via a preferential oxidation mechanism using nanoparticle catalysts consisting of a ruthenium core covered with platinum.

Coherent diffraction experiments and molecular dynamics enable the study of atomic contraction in gold nanocrystals. They reveal a surface-orientation dependence of the atomic bond contraction—remarkably different from the situation in bulk.

Despite the demonstration that nanowires can grow below the eutectic point, a clear understanding of how this happens has not been reached. Video-rate transmission electron microscopy brings new insight into the issue, showing in real time the growth of silicon nanowires with palladium catalysts.

Two-phase materials hold great promise for multifunctional applications. To realize practical devices, it is first necessary to obtain a high degree of control of the phase composition. By taking into account the properties of each phase, it is now possible to control the strain at the interfaces between them in two-component materials, and obtain phase ordering at large scales.

A highly conductive channel, a few nanometres wide, can be reversibly created by an AFM tip operating at room temperature at the interface between two oxide insulators. This discovery could provide a powerful method for the design and realization of electronic circuits at the nanoscale.

Induced multiferroics, where ferroelectricity arises through the magnetic order, have attracted significant interest, despite maximum Curie temperatures of only 40 K. The discovery of multiferroic coupling up to 230 K in CuO therefore represents a major advance towards high-T_C multiferroics.

Modulated proton transport has a significant role in biological processes such as ATP synthesis and in electrochemical energy conversion. Electrostatic gating of proton conduction that can be actively modulated is now shown in aligned mesoporous silica thin-films.

The nature of the charge transport in organic semiconductors is subject to intense research. A study on the thermal and charge transport of single-crystal thin-film polymers now shows close similarities between the transport properties of organic and inorganic semiconductors.

Metamaterials have attracted a great amount of interest, owing to a number of appealing applications such as cloaking. The use of superconducting components now enables the fabrication of metamaterials that could be used to cloak static magnetic fields rather than oscillating light waves.

Controlling and monitoring individual spins is desirable for building spin-based devices. The optical manipulation of the spin of manganese ions in gallium arsenide is now possible. The spins of a small number of ions can be oriented by selecting the polarization of a laser beam. Reduction of the ion concentration enables control of single manganese spins.