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A novel phosphor for glareless white light-emitting diodes
Light-emitting diodes are attractive sources of light used in an increasing range of applications. This study presents a novel europium-based phosphor that gives rise to a substantial reduction in the glare that often makes LEDs uncomfortable to the human eye.
- Hisayoshi Daicho
- , Takeshi Iwasaki
- & Hideo Hosono
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Lightweight nanoporous metal hydroxide-rich zeotypes
Nanoporous zeotypes have applications as catalysts and in gas separation, but they are usually produced as moderately dense silicates and aluminosilicates with relatively low capacities for gas uptake. Here, zeotype structures are reported with very low densities and high total specific pore volumes.
- Benjamin T.R. Littlefield
- & Mark T. Weller
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Measuring the size of individual particles from three-dimensional imaging experiments
The degree of polydispersity of colloidal suspensions is known to have consequences for their physical properties. Kuritaet al. present a general method for determining the sizes of individual particles, and thus the polydispersity, using only the coordinates of the centre positions of spherical particles.
- Rei Kurita
- , David B. Ruffner
- & Eric R. Weeks
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Highly stable Pt monolayer on PdAu nanoparticle electrocatalysts for the oxygen reduction reaction
Platinum is used as a cathode in fuel cells but undergoes dissolution during potential changes, hindering commercial application in electric vehicles. Sasakiet al.report a new class of stable electrocatalysts that consist of platinum monolayers on palladium–gold alloy nanoparticles.
- Kotaro Sasaki
- , Hideo Naohara
- & Radoslav R. Adzic
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Top-down fabricated silicon nanowires under tensile elastic strain up to 4.5%
Strain in Si nanostructures is used to achieve higher carrier mobility, making these devices candidates for the next generation of transistors. Minamisawaet al. fabricate silicon nanowires subject to elastic tensile strain up to 4.5%, exceeding the limit achievable with the use of SiGe virtual substrates.
- R.A. Minamisawa
- , M.J. Süess
- & H. Sigg
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| Open AccessLinear magnetoresistance due to multiple-electron scattering by low-mobility islands in an inhomogeneous conductor
Linear magnetoresistance is a phenomenon observed in many material systems and could be used in magnetic field sensors. This paper uncovers its microscopic origin showing how it arises from multiple scattering of electrons by low-mobility islands within an inhomogeneous high-mobility semiconductor.
- N.V. Kozlova
- , N. Mori
- & A. Patanè
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Highly transparent nonvolatile resistive memory devices from silicon oxide and graphene
Flexible electronic devices are widely considered to have significant potential for a range of applications. Here the authors present a bendable and transparent memory based on graphene electrical contacts and silica as the memory element.
- Jun Yao
- , Jian Lin
- & James M. Tour
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Arrays of giant octagonal and square cylinders by liquid crystalline self-assembly of X-shaped polyphilic molecules
T- and X-shaped polyphilic liquid crystals can generate ordered structures with potential nanotechnology applications. Here, the inability of polyphiles to achieve optimal packing and complete nanophase separation is exploited to produce a flexible two-dimensional honeycomb with giant octagonal and square cylinders.
- Feng Liu
- , Robert Kieffer
- & Carsten Tschierske
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| Open AccessQuasiparticles and Fermi liquid behaviour in an organic metal
The physical properties of organic metals have generally been described in terms of a highly correlated Luttinger liquid. Using angle-resolved photoelectron spectroscopy, Kisset al. measure the Fermi surface of (BEDT-TTF)3Br(pBIB), and find that, in contrast to other systems, it can be described as a Fermi liquid.
- T. Kiss
- , A. Chainani
- & S. Shin
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Quantifying through-space charge transfer dynamics in π-coupled molecular systems
The charge-transfer characteristics of conjugated molecules are important in determining their electronic properties. Using resonant photoemission spectroscopy, Batraet al. quantify the through-space charge transfer in two model conjugated systems with femtosecond resolution.
- Arunabh Batra
- , Gregor Kladnik
- & Latha Venkataraman
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| Open AccessSpin–orbit induced electronic spin separation in semiconductor nanostructures
Achieving spin separation of charged particles in non-uniform magnetic fields is hindered by the Lorentz force. Kohdaet al. demonstrate spin separation in a semiconductor nanostructure by exploiting the effective magnetic field arising from the spin–orbit interaction and achieve highly polarized spin currents.
- Makoto Kohda
- , Shuji Nakamura
- & Junsaku Nitta
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| Open AccessObservation of Landau levels in potassium-intercalated graphite under a zero magnetic field
A signature of the Dirac-like physics of charge carriers in graphene is the occurrence of an anomalous Hall effect, resulting in a quantization of the Landau levels. Guoet al. observe Landau levels of Dirac fermions in potassium-intercalated graphite arising in the absence of an applied magnetic field.
- Donghui Guo
- , Takahiro Kondo
- & Junji Nakamura
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Controllable chirality-induced geometrical Hall effect in a frustrated highly correlated metal
The anomalous Hall effect is a macroscopic manifestation of a quantum mechanical effect. Here, Uelandet al. report the observation of a high Hall conductivity in the heavy-fermion compound UCu5, a metallic system, and explain its origin in terms of geometric frustration effects.
- B.G. Ueland
- , C.F. Miclea
- & J.D. Thompson
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Tunable ferroelectricity in artificial tri-layer superlattices comprised of non-ferroic components
Ferroelectric materials are appealing for use in a range of technological applications. This study demonstrates the onset of ferroelectric behaviour in a superlattice structure that consists of three non-ferroelectric layers, suggesting ferroelectricity can also be induced by interface effects.
- K. Rogdakis
- , J.W. Seo
- & C. Panagopoulos
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First-order coil-globule transition driven by vibrational entropy
The coil-globule transition undergone by polymers in solution delineates a transition from expanded coils to collapsed globules, depending on the polarity of the solvent. This study examines the influence of vibrational entropy on the transition, and finds it can induce a crossover from a second-order to a first-order transition.
- Carlo Maffi
- , Marco Baiesi
- & Paolo De Los Rios
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Enhanced mechanical properties of nanocrystalline boron carbide by nanoporosity and interface phases
The mechanical properties of structural ceramics are characterized by a high degree of fragility and brittleness. This study demonstrates that, contrary to expectation, their brittleness can be reduced substantially by introducing nanopores together with weak grain boundary phases.
- K. Madhav Reddy
- , J.J. Guo
- & M.W. Chen
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Fabrication of flexible and freestanding zinc chalcogenide single layers
Ultrathin inorganic materials hold promise for a variety of applications, including flexible electronics. This work presents a fabrication method that permits the synthesis of large and flexible freestanding layers of zinc selenide that display a high-photocurrent density.
- Yongfu Sun
- , Zhihu Sun
- & Yi Xie
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Proximity-induced high-temperature superconductivity in the topological insulators Bi2Se3 and Bi2Te3
Inducing superconductivity in topological insulators by proximity to superconductors is a promising strategy for quantum computing. Here the authors induce high-temperature superconductivity in the topological insulators Bi2Se3 and Bi2Te3by placing them in contact with a cuprate superconductor.
- Parisa Zareapour
- , Alex Hayat
- & Kenneth S. Burch
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| Open AccessHard magnetic ferrite with a gigantic coercivity and high frequency millimetre wave rotation
Permanent magnets based on magnetic ferrites such as Fe3O4 and Fe2O3 are used in a wide range of applications. This study demonstrates that introducing rhodium into nanoparticles consisting of the ε phase of Fe2O3gives rise to a very high coercivity.
- Asuka Namai
- , Marie Yoshikiyo
- & Shin-ichi Ohkoshi
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Spin-enhanced organic bulk heterojunction photovoltaic solar cells
One of the obstacles to improving the efficiency of organic photovoltaic solar cells is the recombination of polaron pairs at the interface between donor and acceptor molecules. By doping cells with galvinoxyl radicals, Zhanget al. demonstrate a mechanism that overcomes this problem via a spin-flip process.
- Ye Zhang
- , Tek P. Basel
- & Z. Valy Vardeny
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Charge stripe order near the surface of 12-percent doped La2−xSrxCuO4
Charge stripe order has been predicted to be the ground state for the parent compounds of copper oxide superconductors. Using resonant X-ray diffraction, Schüßler-Lagenheineet al. probe the surface region of 12 percent doped La2−xSrxCuO4, and observe charge-stripe order.
- H.-H. Wu
- , M. Buchholz
- & C. Schüßler-Langeheine
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Direct dynamic imaging of non-adiabatic spin torque effects
The torque contributions exerted by spin-polarized currents on magnetic structures are not fully understood due to the difficulty in discerning their relative weight. Pollardet al. propose a novel method to directly determine the value of the competing spin transfer torques by in-situLorentz microscopy.
- S.D. Pollard
- , L. Huang
- & Y. Zhu
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| Open AccessOptical detection of a single rare-earth ion in a crystal
The optical transitions that occur in rare-earth-doped crystals offer promise for quantum information storage and processing. Kolesovet al.report the optical detection of a single praseodymium ion residing in a crystal host by using an excited-state absorption process to enhance its fluorescence yield.
- R. Kolesov
- , K. Xia
- & J. Wrachtrup
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Hygro-responsive membranes for effective oil–water separation
Membrane-based technologies to separate oil–water mixtures are energy-intensive, suffer from fouling or cannot separate a wide range of mixtures. Now, a new membrane is reported that is superhydrophilic and superoleophobic, and can separate a range of oil–water mixtures with high efficiency, without an external energy source.
- Arun K. Kota
- , Gibum Kwon
- & Anish Tuteja
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Optical separation of mechanical strain from charge doping in graphene
The spectral position of Raman peaks is a useful diagnostic for determining the degree of strain and excess electronic charges present in graphene. This study demonstrates that these two contributions can be separated from each other and therefore be obtained at the same time.
- Ji Eun Lee
- , Gwanghyun Ahn
- & Sunmin Ryu
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Flexible and transparent all-graphene circuits for quaternary digital modulations
Signal modulation is a mechanism which embeds an information-carrying signal into a carrier wave to broadcast information and is essential for high-speed communication. Zhonget al. report a flexible, transparent all-graphene modulator circuit performing quaternary modulation schemes with only two transistors.
- Seunghyun Lee
- , Kyunghoon Lee
- & Zhaohui Zhong
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High-mobility and low-power thin-film transistors based on multilayer MoS2 crystals
Molybdenum disulphide offers some tantalizing advantages over graphene as a material with which to fabricate field-effect transistors. Kimet al. present a comprehensive study of field-effect transistors made from multilayer samples of MoS2and find that they can achieve high carrier mobilities.
- Sunkook Kim
- , Aniruddha Konar
- & Kinam Kim
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In situ measurement of exciton energy in hybrid singlet-fission solar cells
Singlet fission converts single singlet excitons into pairs of triplet excitons, and it has been proposed to give additional photocurrent to solar cells. Ehrleret al. use lead selenide nanocrystals of varying sizes to measure the triplet energy in pentacene photovoltaic cells, and achieve efficiencies approaching 5%.
- Bruno Ehrler
- , Brian J. Walker
- & Neil C. Greenham
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| Open AccessAmbient fabrication of flexible and large-area organic light-emitting devices using slot-die coating
Light-emitting electrochromic cells are a promising alternative to organic light-emitting diodes, as their performance is less sensitive to fabrication conditions. Here, a roll-to-roll compatible fabrication of such devices is presented, demonstrating large-area continuous production in ambient conditions.
- Andreas Sandström
- , Henrik F. Dam
- & Ludvig Edman
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Laser-induced ultrafast demagnetization in the presence of a nanoscale magnetic domain network
Understanding ultrafast demagnetisation is key to manipulating magnetic structures on fast timescales, yet laser sources limit the attainable spatial resolution. Here, a soft X-ray high harmonic source enables a high temporal and spatial resolution study of domain demagnetisation in [Co/Pt]30multilayer films.
- Boris Vodungbo
- , Julien Gautier
- & Jan Lüning
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| Open AccessObservation of resistively detected hole spin resonance and zero-field pseudo-spin splitting in epitaxial graphene
Along with its electronic characteristics, the spin properties of graphene have recently received increasing attention in the context of spintronic applications. Using microwave radiation, Maniet al. identify resistively detected spin resonance in monolayer and trilayer graphene sheets and extract the value for the Landé g-factor.
- Ramesh G. Mani
- , John Hankinson
- & Walter A. de Heer
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Skyrmion flow near room temperature in an ultralow current density
Current-induced motion of magnetic nanostructures, such as skyrmions or domain walls, is envisioned as a promising scalable technology for information storage. Yuet al.demonstrate near-room-temperature motion of skyrmions with current densities orders of magnitude lower than previously reported in domain walls.
- X.Z. Yu
- , N. Kanazawa
- & Y. Tokura
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| Open AccessHiggs transition from a magnetic Coulomb liquid to a ferromagnet in Yb2Ti2O7
Quantum spin ice is a magnetic state of matter which can play host to monopole excitations. Using polarized neutron scattering, Changet al. show that the quantum spin ice material ytterbium titanate undergoes a Higgs transition of emergent magnetic monopoles from a Coulomb liquid to a ferromagnetic phase.
- Lieh-Jeng Chang
- , Shigeki Onoda
- & Martin Richard Lees
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| Open AccessLight-induced spiral mass transport in azo-polymer films under vortex-beam illumination
Non-uniform light beams can create patterns in azo-polymer films by inducing mass transport, yet the process is not well understood. Using optical vortex beams, Ambrosioet al. observe the formation of spiral patterns that are surprisingly sensitive to the optical phase, which they explain with a new model.
- Antonio Ambrosio
- , Lorenzo Marrucci
- & Pasqualino Maddalena
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Solderable and electroplatable flexible electronic circuit on a porous stretchable elastomer
The integration of flexible electronics with conventional devices has been hampered by the lack of suitable soldering techniques able to withstand stretching. Jeonget al. use a porous substrate to fabricate biocompatible, stretchable electronics that can be interfaced with commercial components.
- Gi Seok Jeong
- , Dong-Hyun Baek
- & Sang-Hoon Lee
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Topological crystalline insulators in the SnTe material class
Topologically protected states of matter are receiving widespread attention owing to their unusual electronic properties. Using numerical simulations, this study predicts that tin telluride is a physical realization of a new class of materials termed topological crystalline insulators.
- Timothy H. Hsieh
- , Hsin Lin
- & Liang Fu
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Biomimetic layer-by-layer assembly of artificial nacre
Nacre is an organic–inorganic composite biomaterial, which consists of an ordered multilayer structure of crystalline calcium carbonate platelets separated by porous organic layers. Finnemoreet al. present a route to artificial nacre which mimics the natural layer-by-layer biosynthesis.
- Alexander Finnemore
- , Pedro Cunha
- & Ullrich Steiner
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| Open AccessPatterning symmetry in the rational design of colloidal crystals
Patchy colloids are colloidal particles with chemically or physically patterned surfaces that result in complex interactions arising between them. By means of numerical simulations, Romano and Sciortino show that suitably tailored patches can induce the crystallization of patchy colloids into specific crystal structures.
- Flavio Romano
- & Francesco Sciortino
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| Open AccessRoles of icosahedral and crystal-like order in the hard spheres glass transition
The dynamics and structure of the glass transition in liquids is still debated. Using particle-level confocal microscopy, Leocmach and Tanaka investigate supercooled colloidal liquids and distinguish different scenarios for glassy slow dynamics, suggesting that local ordering may only play a minor role.
- Mathieu Leocmach
- & Hajime Tanaka
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| Open AccessStructural correlations in the generation of polaron pairs in low-bandgap polymers for photovoltaics
The electronic and optical properties of polymer semiconductors are largely dictated by their chemical structure. This study examines the nature of the photoexcited states generated in donor–acceptor polymers, and uncovers the dynamics of polaron pairs generation and recombination.
- Raphael Tautz
- , Enrico Da Como
- & Ullrich Scherf
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Realizing a robust practical Majorana chain in a quantum-dot-superconductor linear array
Majorana fermions—the particles renowned for being their own antiparticles—have been proposed as candidates for storing qubits for quantum computers. Sau and Das Sarma propose a method for creating stable Majorana fermions in an array of quantum dots.
- Jay D. Sau
- & S. Das Sarma
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Evidence for charge–vortex duality at the LaAlO3/SrTiO3 interface
Vortex–charge duality is a model that has been proposed for describing the superconducting to insulator transition in disordered thin films. Mehtaet al. report experimental evidence for this duality in the two-dimensional electron gas that arises in LaAlO3/SrTiO3heterostructures.
- M.M. Mehta
- , D.A. Dikin
- & V. Chandrasekhar
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Dynamics of multiple phases in a colossal-magnetoresistive manganite as revealed by dielectric spectroscopy
Correlated electron oxide materials have rich phase diagrams with magnetic or electronic properties. Using a p-n junction configuration, Shenget al. explore the dielectric response of different phases in manganite thin films and uncover their dynamic transport properties.
- Zhigao Sheng
- , Masao Nakamura
- & Yoshinori Tokura
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| Open AccessTwo-dome structure in electron-doped iron arsenide superconductors
The iron pnictides are a class of superconductors that have received widespread interest in recent years. By doping the prototypical material LaFeAsO with hydrogen, this study reveals the existence of a second superconducting dome at higher doping ranges, which arises due to orbital fluctuations.
- Soshi Iimura
- , Satoru Matsuishi
- & Hideo Hosono
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Photoinduced handedness switching in terahertz chiral metamolecules
Chiral metamaterials present interesting ways to manipulate and distinguish between different circular polarizations of light. Zhanget al. realize chiral metamaterials that exhibit photoinduced switching between left- and right-handed circular polarization interactions at terahertz frequencies.
- Shuang Zhang
- , Jiangfeng Zhou
- & Xiang Zhang
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Electronic origin of high-temperature superconductivity in single-layer FeSe superconductor
The exact mechanism for superconductivity in iron-based superconductors remains elusive, but is thought to involve complex interactions between many orbitals. Using angle-resolved photoelectron spectroscopy, Liuet al. report the electronic structure of the single-layer parent compound FeSe.
- Defa Liu
- , Wenhao Zhang
- & X.J. Zhou
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Gate-defined quantum confinement in suspended bilayer graphene
The ability to manipulate single charges is a key requisite for novel nanoelectronic devices. Allenet al. show how to electrostatically confine electrons in suspended bilayer graphene quantum dots by local control of the graphene band structure.
- M. T. Allen
- , J. Martin
- & A. Yacoby
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Tunable conductivity threshold at polar oxide interfaces
The SrTiO3/LaAlO3 system is widely studied because it forms a two-dimensional electron gas at the interface. This study investigates the effects of diluting the LaAlO3 layer with SrTiO3, and finds that the threshold thickness required for the onset of conductivity scales inversely with the fraction of LaAlO3, suggesting an intrinsic origin for the electron gas.
- M.L. Reinle-Schmitt
- , C. Cancellieri
- & P.R. Willmott
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| Open AccessRobust spin crossover and memristance across a single molecule
Switches made up of single molecules form the basis for the concept of molecular electronics. Miyamachiet al.demonstrate that an iron-based spin crossover molecule can be switched between different spin states, provided it is decoupled from a metallic substrate by a thin insulating layer.
- Toshio Miyamachi
- , Manuel Gruber
- & Wulf Wulfhekel