Volume 13 Issue 3, March 2014

With its strategic location and firm commitment to investing in research, Luxembourg has ambitious plans to become a significant player in the international research arena.

By following three empirical rules it is possible to design and fabricate magnetic heterostructures or even devices whose magnetization can be controlled by means of circularly polarized femtosecond laser pulses, instead of applied magnetic fields.

The experimental observation of polariton condensates at room temperature in soft organic materials makes the study of quantum condensed phases easily accessible and opens inroads to optoelectronic devices based on macroscopic quantum phenomena.

The spontaneous organization of semiconductor nanoparticles into uniform pairs of parallel nanorods bridged at their ends illustrates the potential of hierarchical self-assembly processes for the formation of inorganic superstructures with complexity comparable to that of small self-organized biological aggregates.

Knot-shaped micrometric tubes embedded in a liquid crystal induce the formation of defect lines that loop around the knotted tubes to form knots.

Synthetic polymer gels with certain surface chemistries can be glued together by a simple and inexpensive method that uses commercially available silica nanoparticles. Biological tissues can also be joined by this nanotechnological route, eliminating the need for sutures, additional adhesives or chemical reactions.

Solar cells based on colloidal quantum dots require specific charge-extraction strategies that take full advantage of the size-tunable absorption properties of the nanoparticles. This Progress Article reviews the recent engineering efforts aimed at maximizing the power-conversion efficiency of these devices by developing novel architectures as well as by optimizing the morphological and electronic properties of both the electrodes and quantum dot layers.

Remarkably stable excitations known as skyrmions have recently garnered significant attention in condensed-matter systems. It is now shown that skyrmions in thin films of MnSi and Cu₂OSeO₃ can be made to rotate as a result of thermal fluctuations.

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 unusual metallic states arising at the surface of topological insulators have generated significant interest. Now, such topologically protected states are observed by means of tunnelling spectroscopy at the solid-state interface between a topological insulator and a conventional semiconductor.

Colloidal particles dispersed in liquid crystals induce nematic fields and topological defects that are dictated by the topology of the colloidal particles. However, little is known about such interplay of topologies. It is now shown that knot-shaped microparticles in liquid crystals induce defect lines that get entangled with the colloidal knots, and that such mutually tangled configurations satisfy topological constraints and follow predictions from knot theory.

High-resolution atomic force microscopy coupled with a frequency modulation method is used to visualize flexible, monoclonal immunoglobulin G (IgG) antibodies and their interactions with antigens in aqueous solutions. IgG molecules, which individually have Y-shaped structures, self-assemble into hexamers that form crystalline two-dimensional arrangements on a mica substrate, and are observed to retain their immunoactivity within the crystal.

Cavity polaritons have been extensively studied in inorganic materials. An organic polariton condensate is now demonstrated to occur in the strongly interacting regime, at room temperature, in a cavity containing an organic polymer.

Confining light in subwavelength nanowires has posed a challenge to harnessing their potential for integrated photonic devices. Now, it is shown that a high-Q cavity can be achieved by placing a single nanowire into a groove in a photonic crystal resonator.

A promising strategy for achieving information storage devices with low energy consumption is to avoid using applied magnetic fields as a means to manipulate the magnetization of materials. Now, the class of materials that can be switched by all-optical means is shown to extend beyond alloys consisting of rare earths and transition metals.

Although producing 2,5-dimethylfuran (DMF) from 5-hydroxymethylfurfural (HMF) is an attractive way to synthesize renewable fuels, achieving high yields for this reaction has proved difficult. PtCo bimetallic nanoparticle catalysts embedded in hollow carbon nanospheres now show improved catalytic performance for the hydrogenolysis of HMF to DMF (98% yield after 2 hours).

By means of electron microscopy it is shown that two closely spaced crystalline ZnSe nanorods connected by twinning structures can form through a self-limiting self-assembly process. These colloidal nanorod couples have low photoluminescence polarization anisotropy, their composition can be changed by means of a cation-exchange approach, and could be used to investigate the electronic coupling between the individual nanorods.

Glioblastoma multiforme—an aggressive form of brain tumour —is known to migrate along white matter tracts and blood vessels. Now, aligned polycaprolactone nanofibres within a polymeric carrier are shown to guide tumour cells from the primary tumour site to an extracortical hydrogel ‘sink’ and hence lower tumour volume in the brain.

Luxembourg has recently embarked on an ambitious policy to invest in research. In this focus issue we highlight the impact this development is having on materials science in the country, and examine the challenges and opportunities it poses.