Nature Materials contents: January 2014 Volume 13 Number 1 pp 1-97

TABLE OF CONTENTS January 2014 Volume 13, Issue 1 Editorial Research Highlights News and Views Progress Article Letters Articles Corrigendum Subscribe   Facebook   RSS   Recommend to library   Twitter   Advertisement NatureJournals app for ipad The NatureJournals app for iPad now boasts over 25 Nature-branded titles. Subscribe to any journal in the app for $35.99* and gain access to world class research on the move. www.nature.com/content/app/anytitleoffer *Apple exchange rates apply. Limited time offer available on all journals except Scientific Reports. iPad is a trademark of Apple Inc.   Editorial Top Germany's new old way   p1 doi:10.1038/nmat3857 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? Research Highlights Top Improved by integration | Rough with the smooth | Heart twists | Fatigued metallic glasses | Anhydrous polymer electrolyte News and Views Top Water splitting: An adaptive junction   pp3 - 4 Thomas W. Hamann doi:10.1038/nmat3843 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. See also: Article by Lin & Boettcher Organic photovoltaics: Efficient relaxation   pp4 - 5 Daniel Moses doi:10.1038/nmat3842 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. See also: Article by Vandewal et al. Material witness: Joint enterprise   p6 Philip Ball doi:10.1038/nmat3846 Shape-memory materials: Nanoscale oxides shape up   pp6 - 8 Antoni Planes and Lluís Mañosa doi:10.1038/nmat3844 Reversible strains up to 14% driven by changes in temperature or electric field have been realized in a thin film of bismuth ferrite oxide. Directed colloidal assembly: Printing with magnets   pp8 - 9 Changqian Yu, Jie Zhang and Steve Granick doi:10.1038/nmat3845 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'. Nature Materials JOBS of the week Professor of Materials Characterisation The University of Manchester Clare Boothe Luce Assistant Professor Position in Hard Materials University of Delaware Postdoc (1+1 Years) in Metal Oxide Surface Electrochemistry Umeå University More Science jobs from Nature Materials EVENT Frontiers of Computer Simulation in Chemistry and Materials Science 06.02.14 Newport Pagnell, UK More science events from Progress Article Top Spin-torque building blocks   pp11 - 20 N. Locatelli, V. Cros and J. Grollier doi:10.1038/nmat3823 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. Letters Top Observing bulk diamond spin coherence in high-purity nanodiamonds   pp21 - 25 Helena S. Knowles, Dhiren M. Kara and Mete Atatüre doi:10.1038/nmat3805 The photoluminescent properties of electron spins at nitrogen–vacancy (NV) centres are promising for use in quantum information and magnetometry. It is now shown that the coherence times of NV centres in nanodiamonds can be engineered to be comparable to those of bulk diamond. Enhanced oxidation of nanoparticles through strain-mediated ionic transport   pp26 - 30 Andrew Pratt, Leonardo Lari, Ondrej Hovorka, Amish Shah, Charles Woffinden, Steve P. Tear, Chris Binns & Roland Kröger doi:10.1038/nmat3785 Size effects and geometry can significantly modify the properties of nanoparticles with direct impact on their biocompatibility and chemical reactivity. Using high-resolution electron microscopy it is now shown that strain gradients induced in the oxide shell of cuboid Fe nanoparticles can lead to oxide domain formation and shape evolution of the particles. A family of oxide ion conductors based on the ferroelectric perovskite Na0.5Bi0.5TiO3   pp31 - 35 Ming Li, Martha J. Pietrowski, Roger A. De Souza, Huairuo Zhang, Ian M. Reaney, Stuart N. Cook, John A. Kilner & Derek C. Sinclair doi:10.1038/nmat3782 Oxide ion conductors are technologically relevant for applications in electrochemical devices such as sensors, separation membranes and fuel cells. Magnesium doping in Na0.5Bi0.5TiO3—a piezoelectric material that suffers from high leakage conductivity—now results in a family of ionic conductors that could prove significant not only for dielectric-based applications but also for intermediate-temperature solid-oxide fuel cells. Mouldable liquid-crystalline elastomer actuators with exchangeable covalent bonds   pp36 - 41 Zhiqiang Pei, Yang Yang, Qiaomei Chen, Eugene M. Terentjev, Yen Wei & Yan Ji doi:10.1038/nmat3812 A requirement for the reversible mechanical actuation of liquid-crystal elastomers is macroscale alignment. However, current processing techniques do not achieve reliable and robust alignment, which limits the practical use of these materials as actuators and artificial muscles. It is now shown that by introducing polymers with exchangeable covalent bonds, liquid-crystal elastomers can be easily processed and aligned, and subsequently remodelled. Articles Top Landau theory of topological defects in multiferroic hexagonal manganites   pp42 - 49 Sergey Artyukhin, Kris T. Delaney, Nicola A. Spaldin and Maxim Mostovoy doi:10.1038/nmat3786 Rare-earth hexagonal manganites are known for their multiferroic properties. Using parameters calculated from first principles, a theoretical description of the topological defects arising in these systems is now presented. Highly sensitive nanoscale spin-torque diode   pp50 - 56 S. Miwa, S. Ishibashi, H. Tomita, T. Nozaki, E. Tamura, K. Ando, N. Mizuochi, T. Saruya, H. Kubota, K. Yakushiji, T. Taniguchi, H. Imamura, A. Fukushima, S. Yuasa & Y. Suzuki doi:10.1038/nmat3778 Spin-torque diodes enable the detection and rectification of radiofrequencies by means of spin-torque-induced ferromagnetic resonance between nanomagnets. Now, by using magnetic tunnel junctions with a MgO barrier and a FeB free-layer detection sensitivities in excess of those of semiconductor devices are demonstrated. Observation of unconventional edge states in ‘photonic graphene’   pp57 - 62 Yonatan Plotnik, Mikael C. Rechtsman, Daohong Song, Matthias Heinrich, Julia M. Zeuner, Stefan Nolte, Yaakov Lumer, Natalia Malkova, Jingjun Xu, Alexander Szameit, Zhigang Chen & Mordechai Segev doi:10.1038/nmat3783 The propagation of light in photonic crystals with a honeycomb structure mirrors the behaviour of charges in graphene, therefore allowing for the investigation of electronic properties that cannot otherwise be accessed in graphene itself. This approach is now used to predict unexpected edge states that localize in the bearded edges of hexagonal lattices. Efficient charge generation by relaxed charge-transfer states at organic interfaces   pp63 - 68 Koen Vandewal, Steve Albrecht, Eric T. Hoke, Kenneth R. Graham, Johannes Widmer, Jessica D. Douglas, Marcel Schubert, William R. Mateker, Jason T. Bloking, George F. Burkhard, Alan Sellinger, Jean M. J. Fréchet, Aram Amassian, Moritz K. Riede, Michael D. McGehee, Dieter Neher & Alberto Salleo doi:10.1038/nmat3807 The efficiency of organic blends used for photovoltaic applications depends on their ability to convert photoexcited charges into free holes and electrons. It is now demonstrated that the lowermost energetic states formed at the donor/acceptor interface can reach conversion efficiencies close to 100%, and therefore do not behave as traps for charge carriers. See also: News and Views by Moses Detection of subsurface structures underneath dendrites formed on cycled lithium metal electrodes   pp69 - 73 Katherine J. Harry, Daniel T. Hallinan, Dilworth Y. Parkinson, Alastair A. MacDowell and Nitash P. Balsara doi:10.1038/nmat3793 Failure caused by dendrite growth in rechargeable batteries with lithium metal anodes has prevented their widespread applicability. A microtomography study on lithium–polymer–lithium cells now reveals that at the early stage of dendrite formation dendritic structures lie within the electrode, underneath the polymer/electrode interface. Oxygen storage capacity and structural flexibility of LuFe2O4+x (0≤x≤0.5)   pp74 - 80 M. Hervieu, A. Guesdon, J. Bourgeois, E. Elkaïm, M. Poienar, F. Damay, J. Rouquette, A. Maignan & C. Martin doi:10.1038/nmat3809 Layered oxides are promising for many applications ranging from energy conversion and storage to magnetic and electric devices. The oxygen storage ability of ferroelectric LuFe2O4+x is now demonstrated and the storage mechanism is believed to be governed by a complex oxygen intercalation/de-intercalation process with several intermediate metastable states. Adaptive semiconductor/electrocatalyst junctions in water-splitting photoanodes   pp81 - 86 Fuding Lin and Shannon W. Boettcher doi:10.1038/nmat3811 Photoelectrochemical water-splitting devices require integrating electrocatalysts with light-absorbing semiconductors, but understanding charge-transfer processes at interfaces has proved difficult. Ion-permeable electrocatalysts deposited onto TiO2 photoelectrodes now result in adaptive semiconductor/electrocatalyst junctions where both the effective interface barrier height and the photovoltage output change depending on the oxidation state of the electrocatalyst. See also: News and Views by Hamann Epithelial bridges maintain tissue integrity during collective cell migration   pp87 - 96 Sri Ram Krishna Vedula, Hiroaki Hirata, Mui Hoon Nai, Agustí Brugués, Yusuke Toyama, Xavier Trepat, Chwee Teck Lim & Benoit Ladoux doi:10.1038/nmat3814 In wound healing, skin cells collectively migrate to maintain tissue cohesion despite the existence of inhomogeneities in the extracellular environment within the wound bed. Yet how the cell collective responds to heterogeneities in the extracellular matrix is not well understood. Now, it is shown that migrating human keratinocyte cell sheets form suspended multicellular bridges over non-adhesive regions on micropatterned substrates comprising alternating strips of fibronectin and non-adherent polymer. Corrigendum Top Corrigendum: Enabling direct H2O2 production through rational electrocatalyst design   p97 Samira Siahrostami, Arnau Verdaguer-Casadevall, Mohammadreza Karamad, Davide Deiana, Paolo Malacrida, Björn Wickman, María Escudero-Escribano, Elisa A. Paoli, Rasmus Frydendal, Thomas W. Hansen, Ib Chorkendorff, Ifan E. L. Stephens & Jan Rossmeisl doi:10.1038/nmat3841 Top Advertisement NPG Asia Materials Have you read this highly downloaded review recently published in NPG Asia Materials?  A perspective of mesoscopic solar cells based on metal chalcogenide quantum dots and organometal-halide perovskites  Jae Hui Rhee, Chih-Chun Chung, Eric Wei-Guang Diau  Browse and read more open access reviews.    Natureevents is a fully searchable, multi-disciplinary database designed to maximise exposure for events organisers. The contents of the Natureevents Directory are now live. The digital version is available here. 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