Table of contents


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Editorial

Elements in short supply p157

doi:10.1038/nmat2985

In a special issue this month we explore the challenges caused by supply shortages of several important chemical elements.


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Commentary

Managing the scarcity of chemical elements pp158 - 161

Eiichi Nakamura & Kentaro Sato

doi:10.1038/nmat2969

The issues associated with the supply of rare-earth metals are a vivid reminder to all of us that natural resources are limited. Japan's Element Strategy Initiative is a good example of a long-term strategy towards the sustainable use of scarce elements.


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Interview

Purveyor of the rare pp162 - 163

doi:10.1038/nmat2973

The critical shortage of rare-earth elements is a concern for a number of important technologies, but also an opportunity to research alternative materials and technologies, says Alexander King, director of the US Department of Energy's Ames Laboratory.


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Research Highlights

Our choice from the recent literature p164

doi:10.1038/nmat2984


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News and Views

Electron microscopy: The challenges of graphene pp165 - 166

Knut W. Urban

doi:10.1038/nmat2964

A study of nitrogen doping of graphene reveals the potential of high-resolution electron microscopy for imaging charge transfer around chemical bonds.

See also: Article by Meyer et al.


Synthetic vaccines: Immunity without harm pp166 - 168

Abhinav P. Acharya & Niren Murthy

doi:10.1038/nmat2977

Multilamellar lipid vesicles with crosslinked walls carrying protein antigens in the vesicle core and immunostimulatory drugs in the vesicle walls generate immune responses comparable to the strongest live vector vaccines.


Oxide electronics: Interface takes charge over Si pp168 - 169

Darrell G. Schlom & Jochen Mannhart

doi:10.1038/nmat2965

The formation of a two-dimensional electron liquid at the interface between two insulating oxides, now extended to oxides on Si, joins a wealth of observations that reveal how electron transfer between layers is responsible for this unusual effect.


Phase-change materials: Disorder can be good pp170 - 171

Michael Schreiber

doi:10.1038/nmat2972

The observation that disorder leads to a transition from metallic to insulating behaviour in the crystalline phase of GeSb2Te4 provides a new look at its transport properties, crucial for old and new applications of phase-change materials in non-volatile-memory devices.

See also: Article by Siegrist et al.


Colloidal self-assembly: Patchy from the bottom up pp171 - 173

Flavio Romano & Francesco Sciortino

doi:10.1038/nmat2975

The realization of a self-assembled kagome lattice from colloids with attractive hydrophobic patches offers a simple but powerful example of the bottom-up design strategy.


Artificial atoms: Shape the wave pp173 - 175

Massimo Rontani

doi:10.1038/nmat2970

Tunnelling and capacitance spectroscopies are able to image the wavefunctions of electrons in atom-like solid-state systems as they are shaped by an external magnetic field.


Material witness: The smallest metals p175

Philip Ball

doi:10.1038/nmat2979


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Review

Functional soft materials from metallopolymers and metallosupramolecular polymers pp176 - 188

George R. Whittell, Martin D. Hager, Ulrich S. Schubert & Ian Manners

doi:10.1038/nmat2966

The presence of metal centres in synthetic polymers can impart interesting functionality on the resultant material. This Review Article focuses on the use of metal-containing polymers in a diverse range of applications, for example, in emissive and optical materials, in nanomaterials, as sensors, stimuli-responsive gels, catalysts and artifical metalloenzymes.


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Letters

Orbital reflectometry of oxide heterostructures pp189 - 193

Eva Benckiser, Maurits W. Haverkort, Sebastian Brück, Eberhard Goering, Sebastian Macke, Alex Frañó, Xiaoping Yang, Ole K. Andersen, Georg Cristiani, Hanns-Ulrich Habermeier, Alexander V. Boris, Ioannis Zegkinoglou, Peter Wochner, Heon-Jung Kim, Vladimir Hinkov & Bernhard Keimer

doi:10.1038/nmat2958

The occupation of electronic orbitals on the surface and interface of oxide thin films and heterostructures is a key influence over their properties, including magnetism and superconductivity. A new spectroscopy technique now provides the first quantitative, spatially resolved data of orbital occupation in oxide structures.


Observation of the intrinsic pinning of a magnetic domain wall in a ferromagnetic nanowire pp194 - 197

T. Koyama, D. Chiba, K. Ueda, K. Kondou, H. Tanigawa, S. Fukami, T. Suzuki, N. Ohshima, N. Ishiwata, Y. Nakatani, K. Kobayashi & T. Ono

doi:10.1038/nmat2961

Magnetic domain walls can be controlled through a spin torque, which is usually influenced by extrinsic factors, such as defects, that pin the domain walls to specific configurations. It is now shown that intrinsic pinning conditions can be achieved, which will facilitate the development of efficient information storage devices based on domain wall control.

Subject terms: Magnetic materials | Nanoscale materials | Electronic materials


A heteroepitaxial perovskite metal-base transistor pp198 - 201

Takeaki Yajima, Yasuyuki Hikita & Harold Y. Hwang

doi:10.1038/nmat2946

Electronic devices based on complex oxides offer the possibility to connect electrical devices with phenomena such as magnetism and superconductivity. However, existing oxide field-effect transistors have drawbacks such as high operation voltage. The demonstration of a metal-base transistor whose geometry makes use of the strong internal electric fields in oxide heterojunctions may now offer a new platform for oxide electronics.

Subject terms: Electronic materials | Semiconductors | Surface and thin films


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Articles

Disorder-induced localization in crystalline phase-change materials pp202 - 208

T. Siegrist, P. Jost, H. Volker, M. Woda, P. Merkelbach, C. Schlockermann & M. Wuttig

doi:10.1038/nmat2934

Phase-change materials are used in computer memories for their switching between amorphous and crystalline phases. However, even the crystalline state shows disorder, with extremely small electron mean free paths. The discovery that, depending on annealing temperature, this disorder leads to a metal–insulator transition in the crystalline phase provides a completely new look at the transport properties of these compounds.

Subject terms: Electronic materials | Semiconductors

See also: News and Views by Schreiber


Experimental analysis of charge redistribution due to chemical bonding by high-resolution transmission electron microscopy pp209 - 215

Jannik C. Meyer, Simon Kurasch, Hye Jin Park, Viera Skakalova, Daniela Künzel, Axel Groß, Andrey Chuvilin, Gerardo Algara-Siller, Siegmar Roth, Takayuki Iwasaki, Ulrich Starke, Jurgen H. Smet & Ute Kaiser

doi:10.1038/nmat2941

Transmission electron microscopy (TEM) has reached unprecedented resolution and can provide structural information down to the single atomic level. It is now shown that a properly designed experimental analysis also allows the charge distribution around a single atomic dopant to be monitored, demonstrating the possibility of TEM to provide electronic as well as structural information.

Subject terms: Electronic materials | Nanoscale materials | Characterisation and analytical techniques

See also: News and Views by Urban


An octave-bandwidth negligible-loss radiofrequency metamaterial pp216 - 222

Erik Lier, Douglas H. Werner, Clinton P. Scarborough, Qi Wu & Jeremy A. Bossard

doi:10.1038/nmat2950

Metamaterials show many intriguing properties, which are often limited to a narrow range of frequencies. The demonstration of a low-loss broadband metamaterial at radiofrequencies promises applications as enhanced antennas, for example.

Subject term: Optical, photonic and optoelectronic materials

See also: Erratum by Lier et al.


The lithium intercalation process in the low-voltage lithium battery anode Li1+xV1−xO2 pp223 - 229

A. Robert Armstrong, Christopher Lyness, Pooja M. Panchmatia, M. Saiful Islam & Peter G. Bruce

doi:10.1038/nmat2967

Low-voltage intercalation anodes for lithium batteries are important for future applications in portable electronics and electric vehicles. Using a combination of computational methods along with powder X-ray- and neutron-diffraction techniques, the intercalation process for Li1+xV1−xO2, in particular the key role of non-stoichiometry in switching on intercalation, is clarified.

Subject term: Materials for energy


Mesophase behaviour of polyhedral particles pp230 - 235

Umang Agarwal & Fernando A. Escobedo

doi:10.1038/nmat2959

Monte Carlo simulations are performed to study the assembly of polyhedrons into various mesophases and crystalline states. The formation of new liquid-crystalline and plastic-crystalline phases is predicted at intermediate volume fractions and, by correlating these results with particle anisotropy and rotational symmetry, guidelines for predicting phase behaviour are proposed.

Subject terms: Liquid crystals | Granular materials and particle technology | Nanoscale materials | Computation, modelling and theory


Slow dynamics and internal stress relaxation in bundled cytoskeletal networks pp236 - 242

O. Lieleg, J. Kayser, G. Brambilla, L. Cipelletti & A. R. Bausch

doi:10.1038/nmat2939

Actin networks are an excellent model system for studying the mechanical properties of the cell cytoskeleton. Using microscopic methods, actin bundle networks formed in the presence of the crosslinking protein fascin show age-dependent changes in their viscoelastic properties and spontaneous relaxation dynamics in a similar way to glassy, soft materials.

Subject terms: Polymers | Biological materials | Mechanical properties


Interbilayer-crosslinked multilamellar vesicles as synthetic vaccines for potent humoral and cellular immune responses pp243 - 251

James J. Moon, Heikyung Suh, Anna Bershteyn, Matthias T. Stephan, Haipeng Liu, Bonnie Huang, Mashaal Sohail, Samantha Luo, Soong Ho Um, Htet Khant, Jessica T. Goodwin, Jenelyn Ramos, Wah Chiu & Darrell J. Irvine

doi:10.1038/nmat2960

A potent vaccine-delivery system based on interbilayer-crosslinked multilamellar vesicles is reported. The lipid vesicles enable extracellular co-entrapment of protein antigens and immunostimulatory molecules, which are released in vivo, eliciting endogenous T-cell and antibody responses comparable to those for live vaccines.

Subject terms: Biological materials | Biomedical materials | Design synthesis and processing

See also: News and Views by Acharya & Murthy


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Erratum

Engineering spin propagation across a hybrid organic/inorganic interface using a polar layer p252

L. Schulz, L. Nuccio, M. Willis, P. Desai, P. Shakya, T. Kreouzis, V. K. Malik, C. Bernhard, F. L. Pratt, N. A. Morley, A. Suter, G. J. Nieuwenhuys, T. Prokscha, E. Morenzoni, W. P. Gillin & A. J. Drew

doi:10.1038/nmat2962


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Corrigendum


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Erratum

An octave-bandwidth negligible-loss radiofrequency metamaterial p252

Erik Lier, Douglas H. Werner, Clinton P. Scarborough, Qi Wu & Jeremy A. Bossard

doi:10.1038/nmat2980

See also: Article by Lier et al.


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