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| Open AccessCharge state manipulation of qubits in diamond
Point defects in diamond in the form of nitrogen vacancy centres are believed to be promising candidates for qubits in quantum computers. Grotzet al. present a method for manipulating the charge state of nitrogen vacancies using an electrolytic gate electrode.
- Bernhard Grotz
- , Moritz V. Hauf
- & Jose A. Garrido
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Article |
Perpendicular exchange bias in ferrimagnetic spin valves
Exchange bias is a technologically relevant effect that occurs when thin ferromagnetic films are placed in direct proximity to antiferromagnets. Raduet al. show that an exchange bias occurs at room temperature in ferrimagnetic trilayers, in which the magnetization is aligned perpendicular to the structures.
- F. Radu
- , R. Abrudan
- & H. Zabel
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Review Article |
The biology and chemistry of high-valent iron–oxo and iron–nitrido complexes
High-valent iron–oxo and –nitrido complexes are intermediates in the catalytic cycles of various metalloenzymes that activate dioxygen and dinitrogen. Hohenbergeret al. review the advances in the chemistry of model high-valent iron–oxo and –nitrido systems and relate them to our understanding of related enzymes.
- Johannes Hohenberger
- , Kallol Ray
- & Karsten Meyer
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Article |
Room temperature ferromagnetism in Teflon due to carbon dangling bonds
Teflon is a carbon based polymer that cannot be intrinsically ferromagnetic. This study shows that room temperature ferromagnetism can be induced in Teflon tape by applying mechanical stress such as stretching or cutting, which gives rise to dangling carbon bonds.
- Y.W. Ma
- , Y.H. Lu
- & J. Ding
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Article
| Open AccessSelf-assembly of amorphous calcium carbonate microlens arrays
Biological materials efficiently exploit self-assembly of simple constituents to produce complex functional structures such as optical devices. By controlling organic molecules, Leeet al. show fast two-step self-assembly of CaCO3microlens arrays, reminiscent of their biological counterparts.
- Kyubock Lee
- , Wolfgang Wagermaier
- & Peter Fratzl
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Article
| Open AccessMicrowave cavity-enhanced transduction for plug and play nanomechanics at room temperature
Advances in nanoelectromechanical systems have brought improvements in the quality factor of nanomechanical resonators, yet few low-loss transduction schemes exist at high temperature. Using non-dissipative dielectric coupling to a microwave cavity, Faustet al. present an integrated nanomechanical transducer.
- T. Faust
- , P. Krenn
- & E.M. Weig
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Article |
Organic transistors with high thermal stability for medical applications
Organic electronic devices are promising for many applications, particularly in biomedical research, but are hindered by thermal instability and low melting points. Now, organic thin-film transistors are shown with excellent thermal properties that can withstand medical sterilization processes.
- Kazunori Kuribara
- , He Wang
- & Takao Someya
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Article
| Open AccessPtychographic electron microscopy using high-angle dark-field scattering for sub-nanometre resolution imaging
Diffractive imaging can deliver wavelength-scale resolution with X-rays, although its use with electrons is hampered by experimental constraints. By applying ptychographic methods to transmission electron microscopy, Humphryet al. demonstrate sub-nanometre resolution using low-energy electrons.
- M.J. Humphry
- , B. Kraus
- & J.M. Rodenburg
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Article
| Open AccessPrecise hierarchical self-assembly of multicompartment micelles
Multicompartment micelles can be assembled from block copolymers but it is difficult to manipulate their hierarchical superstructures using straightforward concepts. Here, methods are developed that involve the pre-assembly of subunits for the structurally controlled production of micelles.
- André H. Gröschel
- , Felix H. Schacher
- & Axel H.E. Müller
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Article
| Open AccessZigzag line defects and manipulation of colloids in a nematic liquid crystal in microwrinkle grooves
Understanding defects in liquid crystals is important for controlling their structure and self-assembly properties. Here, nematic liquid crystals confined in microwrinkle grooves show new periodic arrangements and zigzag line defects that can trap particles, offering a method for colloid manipulation.
- Takuya Ohzono
- & Jun-ichi Fukuda
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Article |
Three-dimensional imaging of single nanotube molecule endocytosis on plasmonic substrates
Imaging and tracking the motion of single molecules on cell plasma membranes requires high spatial resolution in three dimensions. Honget al. develop a plasmonic ruler based on the fluorescence enhancement of carbon nanotubes on a gold plasmonic substrate, allowing the observation of nanotube endocytosis in three dimensions.
- Guosong Hong
- , Justin Z. Wu
- & Hongjie Dai
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Article
| Open AccessRepeated growth and bubbling transfer of graphene with millimetre-size single-crystal grains using platinum
Grain boundaries in graphene degrade its properties, and large single-crystal graphene is desirable for electronic applications of graphene. Gaoet al. develop a method to produce millimetre-sized hexagonal single-crystal graphene grains, and films composed of the grains, on platinum by chemical vapour deposition.
- Libo Gao
- , Wencai Ren
- & Hui-Ming Cheng
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Article
| Open AccessIntracellular temperature mapping with a fluorescent polymeric thermometer and fluorescence lifetime imaging microscopy
Intracellular temperature mapping has not previously been achieved. Now, a fluorescent polymeric thermometer has been developed that can be used in combination with fluorescence-lifetime imaging microscopy to allow thermometry with spatial and temperature resolutions of 200 nm and 0.18–0.58 ° C.
- Kohki Okabe
- , Noriko Inada
- & Seiichi Uchiyama
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Article
| Open AccessResolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots
Light scattering from nanoscale objects can be dramatically enhanced in the proximity of optical antennas. Here, by studying the amplitude and phase of the light scattered from a tip located at the hot spot of an antenna, the underlying electromagnetic mechanism of this enhancement is resolved.
- P. Alonso-González
- , P. Albella
- & R. Hillenbrand
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Article
| Open AccessBroadband omnidirectional antireflection coating based on subwavelength surface Mie resonators
Minimising reflection from the interface between materials is an important goal for optical devices such as solar cells or photodetectors. Spinelliet al. show almost total loss of reflection over a broad spectral range from a silicon surface using periodic arrays of sub-wavelength silicon nanocylinders.
- P. Spinelli
- , M.A. Verschuuren
- & A. Polman
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Article |
Fully inorganic oxide-in-oxide ultraviolet nanocrystal light emitting devices
Light-emitting diodes in the form of nanocrystals offer promise for environmental and biomedical diagnostics. Brovelliet al. present a method for realizing mechanically robust and chemically stable nanocrystals emitting light in the ultraviolet range.
- Sergio Brovelli
- , Norberto Chiodini
- & Alberto Paleari
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Article
| Open AccessOctave-wide photonic band gap in three-dimensional plasmonic Bragg structures and limitations of radiative coupling
Radiative interactions between oscillators in optical systems produce new optical properties. Here, radiative coupling in a Bragg-fashioned, stacked arrangement of plasmonic structures yields a tunable photonic band gap of up to one octave at optical frequencies.
- Richard Taubert
- , Daniel Dregely
- & Harald Giessen
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Article |
Wide bandgap tunability in complex transition metal oxides by site-specific substitution
Tuning the bandgap of complex transition metal oxides in a manner that preserves their intrinsic properties has so far remained elusive. Choiet al. demonstrate that the bandgap of bismuth titanate can be varied by substitutional alloying with lanthanum cobaltate, without altering its ferroelectric properties.
- Woo Seok Choi
- , Matthew F. Chisholm
- & Ho Nyung Lee
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Article |
Emergence of non-centrosymmetric topological insulating phase in BiTeI under pressure
The spin–orbit interaction affects the electronic structure of many solids to give rise to a host of unusual phenomena. Bahramyet al.theoretically examine its role in the non-centrosymmetric compound BiTeI, and find that under the application of pressure, it leads to topologically insulating behaviour.
- M.S. Bahramy
- , B.-J. Yang
- & N. Nagaosa
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Article
| Open AccessCMOS-based carbon nanotube pass-transistor logic integrated circuits
Field-effect transistors fabricated from carbon nanotubes have been investigated extensively over the past two decades. This study demonstrates a nanotube-based integrated circuit design that substantially improves the speed and power consumption with respect to silicon-based integrated circuits.
- Li Ding
- , Zhiyong Zhang
- & Lian-Mao Peng
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Article
| Open AccessGeneration and control of polarization-entangled photons from GaAs island quantum dots by an electric field
As quantum information and communication experiments grow in sophistication, the need for efficient sources of entangled photons escalates. Using exciton and biexciton emission in GaAs island quantum dots, Ghaliet al. demonstrate the electric field-induced generation of entangled photons with high fidelity.
- Mohsen Ghali
- , Keita Ohtani
- & Hideo Ohno
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Article |
Broadband light management using low-Q whispering gallery modes in spherical nanoshells
Control of light absorption in optical devices, such as solar cells, can be achieved through resonant features like whispering gallery modes. Here, these modes are exploited in spherical silicon nanoshells to enhance absorption over a broad spectral range in nanometre-scale flexible layers.
- Yan Yao
- , Jie Yao
- & Yi Cui
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Article |
Ultrafast heating as a sufficient stimulus for magnetization reversal in a ferrimagnet
The dynamics of spin ordering in magnetic materials is of interest both from a fundamental and an applied point of view. Using a combination of numerical and experimental techniques, Ostleret al. show that the magnetization of a ferrimagnet can be reversed on a timescale of picoseconds solely by heating it.
- T.A. Ostler
- , J. Barker
- & A.V. Kimel
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Article
| Open AccessOptofluidic waveguide as a transformation optics device for lightwave bending and manipulation
By controlling the flow or composition of liquids, optofluidics provides numerous possibilities for devices, and so has great potential for transformation optics. Here, a multi-mode optofluidic waveguide is presented, which manipulates light to produce controllable chirped focussing and interference.
- Y. Yang
- , A.Q. Liu
- & N.I. Zheludev
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Article
| Open AccessTime-resolved ultrafast photocurrents and terahertz generation in freely suspended graphene
Graphene's broad bandwidth makes it promising as a photodetector, but common electronics cannot analyse the currents at high frequencies. Here, using photocurrent measurements, laser-induced carrier generation effects in freely suspended graphene and at graphene–metal interfaces are clarified up to 1 THz.
- Leonhard Prechtel
- , Li Song
- & Alexander W. Holleitner
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Article
| Open AccessSynergistic toughening of composite fibres by self-alignment of reduced graphene oxide and carbon nanotubes
Composite fibres made of polymers reinforced by carbon nanotubes are known for their exceptional toughness. Shinet al. make these composites even tougher, by self-aligning carbon nanotubes and reduced graphene oxide flakes within the polymer matrix.
- Min Kyoon Shin
- , Bommy Lee
- & Seon Jeong Kim
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Article |
Atom-specific spin mapping and buried topological states in a homologous series of topological insulators
Strategies to tune the surface properties of topological insulators are essential, if they are to find use in applications. Using a combination of theoretical and experimental techniques, this study examines how the properties of ordered ternary topological insulators vary with the content of group IV elements.
- Sergey V. Eremeev
- , Gabriel Landolt
- & Evgueni V. Chulkov
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Article
| Open AccessGeometry analysis and systematic synthesis of highly porous isoreticular frameworks with a unique topology
Zhanget al. show that simple geometry analysis can be used to predict how linker length and length ratios affect pore shape and size of porous coordination polymers. The accuracy of the predictions is confirmed by the synthesis of a series of 13 highly porous isoreticular frameworks.
- Yue-Biao Zhang
- , Hao-Long Zhou
- & Xiao-Ming Chen
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Article |
Chemical structures of hydrazine-treated graphene oxide and generation of aromatic nitrogen doping
Parket al. use 13C and 15N solid-state NMR and X-ray photoelectron spectroscopy to study the chemical structure of hydrazine-treated graphite oxide. Hydrazine treatment is shown to lead to the incorporation of aromatic N2moieties at the graphene edges and restore graphitic networks on the basal planes.
- Sungjin Park
- , Yichen Hu
- & Rodney S. Ruoff
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Article |
Practical photon number detection with electric field-modulated silicon avalanche photodiodes
With ever more experiments involving ever fewer photons, there is increasing need for detectors capable of accurately resolving low numbers of photons. By modulating the electric field on a silicon avalanche diode, Thomaset al. show a high-speed device that can discriminate signals from just a few photons.
- O. Thomas
- , Z.L. Yuan
- & A.J. Shields
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Article |
Tunable Dirac cone in the topological insulator Bi2-xSbxTe3-ySey
The surface electronic structure of topological insulators is characterized by a so-called Dirac cone energy dispersion. This study shows that by tuning the compositions in the compound Bi2−xSbxTe3−ySeyone can control the precise features of its Dirac cone structure while keeping it a bulk insulator.
- T. Arakane
- , T. Sato
- & Yoichi Ando
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Article |
Fine structure constant and quantized optical transparency of plasmonic nanoarrays
Under certain conditions, such as those found in low-dimensional systems, materials can show quantized behaviour based only on universal constants. Here, the relative optical transparency of gold nanopillar arrays is shown to change solely in units of the fine structure constant on adjusting array parameters.
- V.G. Kravets
- , F. Schedin
- & A.N. Grigorenko
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Article |
Near room-temperature synthesis of transfer-free graphene films
Current methods for fabricating graphene rely on its transfer from metal surfaces to substrates suitable for device applications. This study demonstrates a transfer-free approach for growing graphene on substrates such as thermally oxidized silicon and plastic that forms the material underneath a nickel film, at the nickel–substrate interface.
- Jinsung Kwak
- , Jae Hwan Chu
- & Soon-Yong Kwon
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Article |
An exactly solvable model for the integrability–chaos transition in rough quantum billiards
The dynamics of isolated quantum systems can either be strongly correlated with their initial state, or chaotic, as they relax into thermal equilibrium. Olshaniiet al. present a simple, exactly solvable model that captures the transition between these two limiting cases, and suggests it may have some universal features.
- Maxim Olshanii
- , Kurt Jacobs
- & Vladimir A. Yurovsky
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Article
| Open AccessObservation of the inverse spin Hall effect in silicon
The spin Hall effect is a spin current induced by an electric current, and its occurrence in semiconductors is a promising route to controlling spins and their transport. Here, the inverse spin Hall effect, in which an electric current is induced by a spin current, is observed in silicon for the first time.
- Kazuya Ando
- & Eiji Saitoh
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Article |
Evidence for the late formation of hydrous asteroids from young meteoritic carbonates
Dating the age of meteorites can tell us when asteroids formed, but uncertainty remains in the Mn–Cr chronometry. This study presents a method for improving Mn/Cr determination and reports an age of 4,563.4 million years ago for carbonates in CM chondrites, which is younger than previous estimates.
- Wataru Fujiya
- , Naoji Sugiura
- & Yuji Sano
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Article |
Electrically driven photon antibunching from a single molecule at room temperature
Single-photon emitters are important for developing quantum technologies, but their integration with existing devices requires them to be driven by electric fields. Here, an organic light-emitting diode is presented that emits single photons from guest molecules in an applied electric field at room temperature.
- Maximilian Nothaft
- , Steffen Höhla
- & Jörg Wrachtrup
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Article |
Propagation stability of self-reconstructing Bessel beams enables contrast-enhanced imaging in thick media
Self-reconstructing laser beams can propagate deep into thick media, making them ideal for light-sheet microscopy of organic matter. By considering the rings of self-reconstructing Bessel beams, Fahrbach and Rohrbach present a technique for improving the contrast and resolution of this approach.
- Florian O. Fahrbach
- & Alexander Rohrbach
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Article
| Open AccessTight finite-key analysis for quantum cryptography
Although they offer significant promise, practical implementations of quantum key distribution are often not as rigorous as theory predicts. This study demonstrates how two instances of such discrepancies can be resolved by taking advantage of an enotropic formulation of the uncertainty principle.
- Marco Tomamichel
- , Charles Ci Wen Lim
- & Renato Renner
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Article
| Open AccessA cobalt complex redox shuttle for dye-sensitized solar cells with high open-circuit potentials
Dye-sensitized solar cells are a promising alternative to traditional inorganic semiconductor-based solar cells. Yumet al. use a molecularly engineered cobalt complex as a redox mediator to achieve an open-circuit voltage of over 1,000 mV in a mesoscopic dye-sensitized solar cell.
- Jun-Ho Yum
- , Etienne Baranoff
- & Michael Grätzel
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Article |
Momentum-dependent multiple gaps in magnesium diboride probed by electron tunnelling spectroscopy
The electronic structure of superconducting magnesium diboride is predicted theoretically to have a distribution of energy gap values. Chenet al. observe this distribution of values experimentally, by means of high-resolution electron tunnelling spectroscopy.
- Ke Chen
- , Wenqing Dai
- & X. X. Xi
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Article
| Open AccessConclusive quantum steering with superconducting transition-edge sensors
Untrustworthy sources or detectors mean that quantum entanglement cannot always be ensured, but quantum steering inequalities can verify its presence. Using a highly efficient system, Smithet al. are able to close the detection loophole and clearly demonstrate steering between two parties.
- Devin H. Smith
- , Geoff Gillett
- & Andrew G. White
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Article |
Biomedical photoacoustics beyond thermal expansion using triggered nanodroplet vaporization for contrast-enhanced imaging
A dual-contrast agent has been developed for combined ultrasound and photoacoustic imaging. This agent uses vaporization for ultrasound contrast enhancement and photoacoustic signal generation, providing significantly higher signals than thermal expansion, the most commonly used photoacoustic mechanism.
- Katheryne Wilson
- , Kimberly Homan
- & Stanislav Emelianov
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Article |
Control of magnetohydrodynamic stability by phase space engineering of energetic ions in tokamak plasmas
Tokamak plasmas suffer from magnetohydrodynamic instabilities, driven by gradients in current density or pressure, but techniques to control them are power-hungry and reduce reactor efficiency. Here, an efficient method to control such instabilities using asymmetric ion populations is demonstrated at JET.
- J.P. Graves
- , I.T. Chapman
- & M. Jucker
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Article |
Mechanism of supercooled droplet freezing on surfaces
The mechanism through which ice forms on surfaces is of broad technological relevance. This study examines the manner in which ice forms on so-called 'icephobic' surfaces, and demonstrates that simple changes in the environmental conditions can render the icephobicity ineffective.
- Stefan Jung
- , Manish K. Tiwari
- & Dimos Poulikakos
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Article
| Open AccessPhotoswitchable gel assembly based on molecular recognition
Self-assembly through molecular recognition events is used in the production of functionalized materials. This study shows that macroscopic gel assembly can be regulated through photoisomerization of an azobenzene moiety that interacts differently with two host molecules.
- Hiroyasu Yamaguchi
- , Yuichiro Kobayashi
- & Akira Harada
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Article
| Open AccessViolation of a Leggett–Garg inequality with ideal non-invasive measurements
Quantum mechanics predicts that objects can simultaneously exist in a superposition of two states. Kneeet al.propose and demonstrate experimentally a protocol which fully confirms this prediction, by testing the so-called Leggett–Garg inequality in a non-invasive manner.
- George C. Knee
- , Stephanie Simmons
- & Simon C. Benjamin
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Article
| Open AccessMeasurement of finite-frequency current statistics in a single-electron transistor
Fluctuations of the electrical current in nanoscale devices reveal important details of the physical processes occurring inside them. Using a quantum point contact placed in its vicinity, Ubbelohde et al. measure the electrical fluctuations in a single-electron transistor, and determine the dynamical features of the transport.
- Niels Ubbelohde
- , Christian Fricke
- & Rolf J. Haug
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Article
| Open AccessApproaching the ideal elastic limit of metallic glasses
The elastic limit represents the maximum stress and strain a material can withstand and is well characterized in many crystalline solids, yet remains elusive for metallic glasses. Here, this limit is investigated in submicron metallic glass structures and is found to be twice as high as that of bulk samples.
- Lin Tian
- , Yong-Qiang Cheng
- & Evan Ma