Volume 10 Issue 4, April 2011

The high critical temperature and magnetic field in cuprates and Fe-based superconductors are not enough to assure applications at higher temperatures. Making these superconductors useful involves complex and expensive technologies to address many conflicting physics and materials requirements.

Superconductivity has gone from a rare event to a ground state that pops up in materials once considered improbable, if not impossible. Although we cannot predict its occurrence yet, recent discoveries give us some clues about how to look for new — hopefully more useful — superconducting materials.

John Clarke told Nature Materials about his work on superconducting quantum interference devices — SQUIDs — and his fascination with their applicability to many fields, from medicine to geophysics to quantum information and cosmology.

Embedding magnesium nanoparticles in a gas-selective polymer prevents their oxidation under ambient conditions while enabling reversible hydrogen storage.

Memory effects resulting from frustration and topology in nematic liquid crystals confined in bicontinuous structures may enable the fabrication of geometrically functionalized materials.

The interaction between ferroelectric distortion and two rotational modes in some transition-metal oxides promises a strategy for strong magnetoelectronic coupling, possibly at room temperature.

The imaging mode of scanning transmission electron microscopy known as annular bright-field has reached enough sensitivity to image columns of the lightest of elements within a crystal.

Knowledge of the symmetry of the superconducting order parameter is essential to understand the origin of superconductivity itself. Studies on the recently discovered heavily doped Fe₂Se₂ now show that in these compounds the order parameter has a relatively simple symmetry compared with most other Fe-based superconductors, questioning again the generality of the results obtained so far.

The resolution of electron microscopy has increased through the years, and scientists have been able to measure progressively lighter elements. The ultimate goal has now been reached with the imaging of hydrogen atoms.

Using boron nitride as a substrate for graphene has been suggested as a promising way to reduce the disorder in graphene caused by space fluctuations. It is now shown by scanning tunnelling microscopy that graphene conforms perfectly to boron nitride and the charge fluctuations are minimal compared with the conventionally used substrate, silica. Boron nitride could really be the natural graphene substrate.

Producing materials capable of simultaneously absorbing hydrogen and releasing it on-demand is challenging. An air-stable composite material consisting of magnesium nanocrystals embedded in a polymer matrix is now shown to exhibit both high hydrogen-storage density and rapid kinetics.

Because nanotubes are generally prepared from their constituent elements at high temperatures, it is difficult to control their size, shape and electronic states. A bottom-up approach for the room-temperature fabrication of an assembly of infinite square-prism-shaped nanotubes with high tunability, using metal ions and organic molecules as building blocks, is now reported.

One of the key loss mechanisms in the operation of organic solar cells is the separation and extraction of the generated charge carriers from the active region. The use of a ferroelectric layer is now shown to create large internal electric fields, resulting in an enhanced carrier extraction and increased device efficiency.

Computer simulations of nematic liquid crystals confined in bicontinuous porous geometries show that frustration and topology lead to multiple, metastable trajectories of defect lines that can be memorized on application of external fields. These topologically enabled metastable states could be exploited to optically functionalize orientationally ordered materials.

Explaining why interactions of metal particles with oxide supports can improve their catalytic performance has proved challenging. The origin and nature of metal–oxide interactions on industrially important platinum–ceria catalysts are now clarified, together with the dependence of the catalytic activity on the structure of the support.

Inflatable balloon catheters are widely used in many surgical and diagnostic procedures. Such catheters have now been used as a platform for a collection of components including semiconductor devices, sensors and actuators, and these multifunctional catheters probed for their use in cardiac-related applications.

The optical properties and biocompatibility of nanovesicles composed of self-assembled porphyrin bilayers are investigated. These nanovesicles—termed porphysomes, with liposome-like structure and loading capacity—are shown to be multimodal contrast agents for photoacoustic tomography and fluorescence imaging in biomedical applications.

One hundred years after its discovery by Heike Kamerlingh Onnes, superconductivity is still one of the most fascinating and challenging topics in condensed-matter physics. We celebrate the anniversary with a number of editorial articles about some successful applications of superconductors and the obstacles that limit their wider use.