Science in the open - p611

doi:10.1038/nmat2497

As moves towards open-access schemes gain momentum, the choice between 'author pays' and subscription-based models may come down to fundamental business considerations rather than limits in access to original research.

Full Text - Science in the open | PDF (181 KB) - Science in the open

Research highlights - p612

doi:10.1038/nmat2498

Full Text - Research highlights | PDF (155 KB) - Research highlights

Metamaterials: A cat's eye for all directions - pp613 - 614

Mark R. Dennis

doi:10.1038/nmat2500

Metamaterials have seen many exciting applications. A design that is able to circumvent singularities in refractive index now allows a broad range of new applications, including an omnidirectional retroreflector.

Full Text - MetamaterialsA cat's eye for all directions | PDF (316 KB) - MetamaterialsA cat's eye for all directions

See also: Letter by Ma et al.

Liquid crystals: Printed actuators in a flap - pp614 - 615

Peter Palffy-Muhoray

doi:10.1038/nmat2502

Solid liquid crystals couple orientational order and mechanical strain, enabling fundamentally new mechanisms of actuation. Depositing the materials using inkjet printing allows precise control of their shapes and composition, producing devices with new microfluidic applications.

Full Text - Liquid crystalsPrinted actuators in a flap | PDF (241 KB) - Liquid crystalsPrinted actuators in a flap

See also: Article by van Oosten et al.

Iron-based superconductors: Vital clues from a basic compound - pp615 - 616

Bernd Büchner & Christian Hess

doi:10.1038/nmat2501

Investigation of the phase diagram of the structurally simple compound FeSe may prove instrumental in raising the transition temperature in Fe-based superconductors and in understanding magnetic-mediated superconductivity.

Full Text - Iron-based superconductorsVital clues from a basic compound | PDF (203 KB) - Iron-based superconductorsVital clues from a basic compound

See also: Letter by Medvedev et al.

Material witness: Cross purposes - p617

Philip Ball

doi:10.1038/nmat2499

Full Text - Material witnessCross purposes | PDF (164 KB) - Material witnessCross purposes

Liquid crystals: More than display fillings - pp617 - 618

Ralf Stannarius

doi:10.1038/nmat2503

With liquid-crystal displays now ubiquitous in everyday life, liquid-crystal research is moving beyond these applications and evolving in entirely new and unexpected directions.

Full Text - Liquid crystalsMore than display fillings | PDF (244 KB) - Liquid crystalsMore than display fillings

Ionic-liquid materials for the electrochemical challenges of the future - pp621 - 629

Michel Armand, Frank Endres, Douglas R. MacFarlane, Hiroyuki Ohno & Bruno Scrosati

doi:10.1038/nmat2448

Abstract - Ionic-liquid materials for the electrochemical challenges of the future | Full Text - Ionic-liquid materials for the electrochemical challenges of the future | PDF (640 KB) - Ionic-liquid materials for the electrochemical challenges of the future

Electronic and magnetic phase diagram of -Fe_1.01Se with superconductivity at 36.7 K under pressure - pp630 - 633

S. Medvedev, T. M. McQueen, I. A. Troyan, T. Palasyuk, M. I. Eremets, R. J. Cava, S. Naghavi, F. Casper, V. Ksenofontov, G. Wortmann & C. Felser

doi:10.1038/nmat2491

Superconductivity was recently observed in the binary iron-based compound, FeSe. It is now shown that under pressure, the transition temperature can rise above 36 K. In addition, no static magnetic ordering is observed for this system, contrary to FeAs superconductors.

First Paragraph - Electronic and magnetic phase diagram of : [beta]: -Fe: 1.01: Se with superconductivity at 36.7[thinsp]K under pressure | Full Text - Electronic and magnetic phase diagram of -Fe1.01Se with superconductivity at 36.7 K under pressure | PDF (44,722 KB) - Electronic and magnetic phase diagram of -Fe1.01Se with superconductivity at 36.7 K under pressure

Subject Categories: Magnetic materials | Superconductors

See also: News and Views by Büchner & Hess

Periodic rotation of magnetization in a non-centrosymmetric soft magnet induced by an electric field - pp634 - 638

M. Saito, K. Ishikawa, S. Konno, K. Taniguchi & T. Arima

doi:10.1038/nmat2492

The electric control of magnetism in magnetic devices has remained problematic, particularly as energy losses due to current flow can be large. The demonstration of electric control of magnetization in a non-centrosymmetric insulating magnetic material therefore represents a new strategy for future applications.

First Paragraph - Periodic rotation of magnetization in a non-centrosymmetric soft magnet induced by an electric field | Full Text - Periodic rotation of magnetization in a non-centrosymmetric soft magnet induced by an electric field | PDF (2,047 KB) - Periodic rotation of magnetization in a non-centrosymmetric soft magnet induced by an electric field | Supplementary information

Subject Categories: Electronic materials | Magnetic materials

An omnidirectional retroreflector based on the transmutation of dielectric singularities - pp639 - 642

Yun Gui Ma, C. K. Ong, Tomá Tyc & Ulf Leonhardt

doi:10.1038/nmat2489

Metamaterials allow the design of new functionality through the engineered control of light propagation, although broadband operation with these materials requires singularities in their refractive index. As a first example of a technique that uses a topological defect to achieve such behaviour in a real system, an omnidirectional metamaterial retroreflector is demonstrated.

First Paragraph - An omnidirectional retroreflector based on the transmutation of dielectric singularities | Full Text - An omnidirectional retroreflector based on the transmutation of dielectric singularities | PDF (1,172 KB) - An omnidirectional retroreflector based on the transmutation of dielectric singularities

Subject Categories: Optical, photonic and optoelectronic materials | Computation, modelling and theory

See also: News and Views by Dennis

Engineering light absorption in semiconductor nanowire devices - pp643 - 647

Linyou Cao, Justin S. White, Joon-Shik Park, Jon A. Schuller, Bruce M. Clemens & Mark L. Brongersma

doi:10.1038/nmat2477

Quantum confinement effects have an important role in photonic devices. However, rather than seeking perfect confinement of light, leaky-mode resonances are shown to be ideally suited for enhancing and spectrally engineering light absorption in nanoscale photonic structures.

First Paragraph - Engineering light absorption in semiconductor nanowire devices | Full Text - Engineering light absorption in semiconductor nanowire devices | PDF (397 KB) - Engineering light absorption in semiconductor nanowire devices | Supplementary information

Subject Categories: Optical, photonic and optoelectronic materials | Nanoscale materials

Three-dimensional nanopillar-array photovoltaics on low-cost and flexible substrates - pp648 - 653

Zhiyong Fan, Haleh Razavi, Jae-won Do, Aimee Moriwaki, Onur Ergen, Yu-Lun Chueh, Paul W. Leu, Johnny C. Ho, Toshitake Takahashi, Lothar A. Reichertz, Steven Neale, Kyoungsik Yu, Ming Wu, Joel W. Ager & Ali Javey

doi:10.1038/nmat2493

Solar power is an important part of the strategy towards using more renewable energy. The development of low-cost photovoltaic nanopillar structures fabricated on thin aluminium substrates will contribute to this effort, as it promises new applications for flexible, mass-produced solar cells.

First Paragraph - Three-dimensional nanopillar-array photovoltaics on low-cost and flexible substrates | Full Text - Three-dimensional nanopillar-array photovoltaics on low-cost and flexible substrates | PDF (1,189 KB) - Three-dimensional nanopillar-array photovoltaics on low-cost and flexible substrates | Supplementary information

Subject Categories: Optical, photonic and optoelectronic materials | Materials for energy

Atomic-scale imaging of individual dopant atoms in a buried interface - pp654 - 658

N. Shibata, S. D. Findlay, S. Azuma, T. Mizoguchi, T. Yamamoto & Y. Ikuhara

doi:10.1038/nmat2486

Aberration-corrected microscopy can provide structural information with atomic precision. It is now shown that even single impurity atoms in a buried interface can be imaged, provided that a particular imaging mode is used. This result can lead to a much clearer understanding of advanced materials and devices that make use of the properties of interfaces.

First Paragraph - Atomic-scale imaging of individual dopant atoms in a buried interface | Full Text - Atomic-scale imaging of individual dopant atoms in a buried interface | PDF (1,408 KB) - Atomic-scale imaging of individual dopant atoms in a buried interface | Supplementary information

Subject Categories: Surface and thin films | Characterisation and analytical techniques

Sequential click reactions for synthesizing and patterning three-dimensional cell microenvironments - pp659 - 664

Cole A. DeForest, Brian D. Polizzotti & Kristi S. Anseth

doi:10.1038/nmat2473

'Click' chemistry has been broadly exploited, but the intrinsic toxicity of the reactions involved makes its translation to biological applications troublesome. Copper-free click chemistry avoids the problems of toxicity, enabling direct encapsulation of cells within click hydrogels. Tailoring of the gels with biological functionalities is also enabled in real time with micrometre-scale resolution.

First Paragraph - Sequential click reactions for synthesizing and patterning three-dimensional cell microenvironments | Full Text - Sequential click reactions for synthesizing and patterning three-dimensional cell microenvironments | PDF (1,133 KB) - Sequential click reactions for synthesizing and patterning three-dimensional cell microenvironments | Supplementary information

Subject Categories: Polymers | Biomedical materials

Selective positioning of organic dyes in a mesoporous inorganic oxide film - pp665 - 671

Kyungtae Lee, Se Woong Park, Min Jae Ko, Kyungkon Kim & Nam-Gyu Park

doi:10.1038/nmat2475

Although sequential adsorption of dyes in TiO₂ electrodes is ideal for extending the range of light absorption in dye-sensitized solar cells, high-temperature processing has so far limited its application. A method for the selective positioning of organic dye molecules with different absorption ranges is now reported in a mesoporous inorganic oxide film.

Abstract - Selective positioning of organic dyes in a mesoporous inorganic oxide film | Full Text - Selective positioning of organic dyes in a mesoporous inorganic oxide film | PDF (3,810 KB) - Selective positioning of organic dyes in a mesoporous inorganic oxide film

Subject Categories: Materials for energy | Porous materials

The dynamic organic p–n junction - pp672 - 676

Piotr Matyba, Klara Maturova, Martijn Kemerink, Nathaniel D. Robinson & Ludvig Edman

doi:10.1038/nmat2478

The light-emitting electrochemical cell (LEC) is one application of organic semiconductors. Scanning kelvin probe microscopy and light-emission data obtained from operational planar LECs provide insight into the devices. The measured electrostatic potential profiles confirm that there is in situ formation of a dynamic p–n junction in the organic semiconductor during operation.

Abstract - The dynamic organic p-n junction | Full Text - The dynamic organic p–n junction | PDF (874 KB) - The dynamic organic p–n junction | Supplementary information

Subject Categories: Semiconductors | Molecular electronics | Polymers

Printed artificial cilia from liquid-crystal network actuators modularly driven by light - pp677 - 682

Casper L. van Oosten, Cees W. M. Bastiaansen & Dirk J. Broer

doi:10.1038/nmat2487

The manufacture of polymeric microactuators is complicated when using techniques like lithography, but inkjet printing can be used to deposit self-organizing liquid-crystal networks instead. Printing sub-units with different inks is easily scalable and creates light-driven actuators with sections that can be individually addressed to mimic the flapping movements of cilia.

Abstract - Printed artificial cilia from liquid-crystal network actuators modularly driven by light | Full Text - Printed artificial cilia from liquid-crystal network actuators modularly driven by light | PDF (1,130 KB) - Printed artificial cilia from liquid-crystal network actuators modularly driven by light

Subject Categories: Liquid crystals | Polymers

See also: News and Views by Palffy-Muhoray

A general phase-transfer protocol for metal ions and its application in nanocrystal synthesis - pp683 - 689

Jun Yang & Jackie Y. Ying

doi:10.1038/nmat2490

Metal nanoparticles can be prepared with good control of particle size and shape by solution-state chemistry, but controlling their physicochemical properties remains a challenge. A generic protocol for transferring metal ions from water to an organic medium is now used to synthesize a range of metallic and semiconductor nanoparticles having multiple functionalities.

Abstract - A general phase-transfer protocol for metal ions and its application in nanocrystal synthesis | Full Text - A general phase-transfer protocol for metal ions and its application in nanocrystal synthesis | PDF (5,696 KB) - A general phase-transfer protocol for metal ions and its application in nanocrystal synthesis | Supplementary information

Subject Categories: Nanoscale materials | Design synthesis and processing