Volume 8 Issue 4, April 2009

To counter the decreasing interest in scientific studies, the PhysiScope at the University of Geneva conveys scientific excitement to teenagers by offering an entertaining and practical way to discover physics.

Anisotropic assembly of isotropic nanoparticles is observed in a polymer nanocomposite system and leads to considerable improvements in mechanical properties. The relatively simple sample preparation process means the approach could be used for large-scale manufacture of nanocomposites.

A large modulation of magnetic moments in superconductor/ferromagnet superlattices raises intriguing questions about the interaction between these competing states.

Non-toxicity in multifunctional inorganic nanoparticles is rare. However, with careful engineering of silicon-based nanoparticles they can be used in vivo as imaging and drug-delivery agents and later degraded and cleared without toxic effects.

Muon and neutron experiments on the new FeAs-based superconductors reveal phase diagrams and spin excitation modes with striking similarities to a wide range of other unconventional superconductors.

In non-conventional superconductors, it is usually found that superconductivity emerges in the vicinity of a critical point where antiferromagnetic order gradually disappears—corresponding to a second-order transition. Investigation of the newly discovered iron pnictide superconductors challenges this picture, showing an abrupt, first-order transition.

In non-conventional superconductors, the competition of magnetic order and superconductivity seems to be a key element for the origin of superconductivity. Investigation of the newly discovered iron-pnictides superconductors challenges this picture, showing a coexistence of superconductivity and magnetism.

Oxide heterostructures offer new functionality based on the interaction of order parameters across the heterostructure interfaces. In particular, it is now demonstrated that superconducting layers can induce giant modulations of magnetization in adjacent ferromagnetic layers.

Layered lithium nickel-rich oxides are attractive as cathodes for rechargeable lithium batteries. A concentration-gradient material based on manganese nickel cobalt oxide showing high capacity and thermal stability could prove advantageous for batteries used in plug-in hybrid electric vehicles.

The development of a direct ethanol fuel cell has been hampered by ethanol’s inefficient and slow oxidation. A ternary electrocatalyst consisting of platinum and rhodium deposited on carbon-supported tin dioxide nanoparticles is now shown to oxidize ethanol to carbon dioxide with high efficiency by splitting C–C bonds at room temperature.

Nanomaterials that can circulate in the body hold great potential to diagnose and treat disease, but suffer from problems such as toxicity. Porous silicon nanoparticles have now been engineered to concomitantly image tumours or organs within the body, deliver therapeutics and resorb in vivo into benign components that clear renally.

What drives a phase transition in the heavy-fermion compound URu₂Si₂ is one of the major unsolved problems in condensed-matter physics. Numerical calculations now demonstrate how antiferromagnetic ordering leads to a symmetry breaking that alters the material’s band structure and therefore its electronic properties.

Molecular rotors have seen considerable interest as functional molecules on surfaces or for applications as memory devices. However, it is now shown that molecular rotation may also be used to induce ferroelectricity in a molecule.

Polymer crystals have a range of melting temperatures, therefore simultaneous melting and crystallization can take place. New crystals are seeded from some of the initial crystalline material, and as the orientation of the second-generation material is correlated with the starting crystal, orientated arrays of polymer crystals are produced.

Anisotropic superstructures produced by the self-assembly of spherical nanoparticles are realized. Uniformly grafting polymer chains onto inorganic spherical nanoparticles produces particles with amphiphile-like behaviour. Mixing these with monodisperse polymer facilitates the self-assembly of numerous anisotropic nanocomposites.

Knowledge of the microscopic structure is essential for understanding the properties of materials and to design functional devices. Electron microscopy and X-ray imaging have been used for decades to 'look' inside matter. The articles in this Insight aim to illustrate some of the most outstanding advances in instrumentation and computation abilities of these techniques that have led to unprecedented precision in terms of spatial resolution and sensitivity to composition and physical properties.