Articles in 2013

Topological crystalline insulators are characterized by metallic states originating from crystal symmetries. A transistor device that takes advantage of the quantum properties of the topological crystalline insulating materials SnTe and Pb_1−xSn_xSe(Te) is now proposed.

Freshly re-elected, there seem to be few radical changes ahead for Angela Merkel's government. Her politics have been successful, but will Germany's neighbours start to benefit too?

A study on carrier-collection efficiency in various organic photovoltaic systems now reveals that ultrafast relaxation of photoexcitations within the manifold of charge-transfer states does not impede mobile charge carrier generation.

Reversible strains up to 14% driven by changes in temperature or electric field have been realized in a thin film of bismuth ferrite oxide.

The energetic and kinetic behaviours of water-oxidation catalysts deposited on semiconductor electrodes are probed in situ, elucidating the junction formed between them, and transforming the design principles of the catalysts.

Planar patterns of colloidal microparticles have been manufactured with high yield over square centimetre areas by using magnetic-field microgradients in a paramagnetic fluid. This approach could evolve into technology capable of printing three-dimensional objects through programmable and reconfigurable 'magnetic pixels'.

Memory devices based on the spin-transfer-torque effect offer a range of attractive properties, such as speed of operation and low energy cost. This Progress Article outlines a strategy for assembling different nanodevices based on the spin-torque effect to achieve qualitatively different computing architectures.

The friction of surfaces in relative motion and separated by a few nanometres is thought to be dominated by electronic effects. It is now found that the friction sensed by an AFM tip oscillating above a NbSe₂ surface takes the form of giant dissipation peaks, and that the peaks are related to a hysteresis cycle where the oscillating tip locally pumps 2π slips in the phase of a charge-density wave.

Although it has been shown that engineering of conducting polymers such as poly(3,4-ethyldioxythiophene) can improve the Seebeck coefficient and the figure of merit ZT of these materials, the mechanisms underlying this improved thermoelectric behaviour are still not fully understood. It is now reported that the band structure of semicrystalline films of these bipolaronic polymers, resembling that of inorganic semi-metals used for thermoelectric applications, can explain these findings.

Understanding the thermal transport properties of superlattice structures is relevant to a number of possible practical applications. Now, the scattering of phonons in oxide superlattices is shown to undergo a crossover from an incoherent to a coherent regime, which in turn strongly alters their thermal behaviour.

Bose–Einstein condensates of exciton–polaritons have been stabilized in a range of crystalline systems. Now, polaritons are shown to condense at room temperature using a microcavity within an organic polymer.

The imaging of tumours is challenging because of the wide range of different cancers. Now, the rapid detection of tumours, independent of type, is achieved using a nonlinear amplification strategy that employs ultrasensitive pH-responsive fluorescent nanoparticles that illuminate within tumour neovasculature or in response to the tumour’s acidic extracellular environment.

The interplay between the electronic and magnetic degrees of freedom in multiferroic materials offers promise for a range of applications. Now, a technique for imaging the magnetoelectric domains directly is developed, and demonstrated on the hexagonal manganite ErMnO₃.