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Indium selenide (InSe) is a promising two-dimensional photodetector material. However, the photogenerated electron-hole pairs are easy to recombine in simplex InSe semiconductor. Here, we design InSe-based van der Waals heterostructure, InSe/antimonene (β-Sb), based on first-principles. InSe/β-Sb heterostructure possesses intrinsic type-II electronic structure. Simultaneously, the work function of InSe (β-Sb) layer is −5.7 eV (−4.5 eV) which also promotes electrons transfer. In addition, the good optical absorption performance of InSe and β-Sb sublayer is preserved in the heterostructure. Moreover, different stacking mode between InSe/β-Sb does not affect the efficient carrier separation which is convenient to the application of optoelectronics.

Using first-principles calculations, we study the growth process of bismuth (Bi) films on Cu (111) substrate. By analyzing the formation mechanism of single layer α‑bismuthene and stability of multilayered Bi layers, we reveal that Bi atoms show quasi-one-dimensional growth model by developing periodic zigzag chains, and eventually form a Bi atomic layer on Cu (111) surface. Flat surface α‑bismuthene (Fα-Bi) can be formed by depositing two Bi atomic layers on Cu (111) and maintains its stability below 60 K. In the multilayered Bi atomic layers, the stability of Bi films shows an oscillatory behavior. It is more stable for Bi films with even layers. The charge density between even and odd films shows that the stability is associated with the saturation of pz orbital of Bi atoms. Besides, the distorted surface α‑bismuthene (Dα-Bi) can maintain its stability up to 450 K on Cu (111) surface. Further study shows that the Cu substrate strongly affects the properties of Fα-Bi than that of Dα-Bi. Our studies provide guidance for fabricating stable Bi (110) thin films based devices.

Grain boundaries (GBs) in polycrystalline graphene could significantly modulate the physicochemical properties of graphene films, and have attracted intense interest. However, fundamental magnetotransport mechanisms of GBs in bilayer graphene grown by chemical vapour deposition (CVD) are scarcely reported. In this work, we synthesize bilayer graphene bicrystals on polycrystalline Cu foils and measure the electronic properties of such grains as well as of individual graphene grain boundaries. Interestingly, the pronounced metallic character of GB is observed, which is dramatically different from individual grains. Large linear magnetoresistance in graphene bicrystals is observed, which attributes to inhomogeneous charge transport, decorated by quantum interference effects at low temperatures. The measurement data show that individual boundaries between coalesced grains impede electrical transport, suppress the magnetoresistance and enhance intervalley scattering, leading to degradation of electrical performance of CVD graphene. Nevertheless, GBs embedded in a perfect graphene sheet can tune its electronic structure at the nanoscale, act as quasi-one-dimensional metallic wires and can be used as good candidates for strong magnetic field sensors. This work is beneficial to the fundamental understanding of the role of GBs in CVD-grown graphene and opens a potential avenue of application for polycrystalline bilayer graphene in functional devices.

The effect of in-plane uniaxial strain on band structures and electronic properties of graphene/blue phosphorene (Gr/BPh) bilayer has been investigated by using first-principles calculations. The results show that the intrinsic electronic properties of graphene and blue phosphorene are preserved well in the unstrained bilayer. Upon the application of in-plane uniaxial strain, the band gap of the Gr/BPh bilayer can be easily opened by ∼120 meV near ±2%, and the value of band gap increases with increasing the strain value. A maximum gap value ∼240 meV is obtained around ±4% strain. By analyzing the projected density of states and charge density differences, we reveal that the opened band gap under strain is closely related to the change in electronic structure of Gr/BPh bilayer, which is greatly influenced by the electron redistribution between graphene and BPh layers as well as the orbital hybridizations between carbon and phosphorus atoms. Further study finds that the band gap can not be opened when the in-plane biaxial strain is applied to the Gr/BPh bilayer. The present work provides us an effective avenue to tune the electronic structures and band gap for Gr/BPh bilayer.

Mixed-heterostructures have received much attention due to their broader application in functional devices. Here, we investigate the strain effect on structural and electronic properties of 2D WSe2/1D ZnO nanoribbon (WSe2/ZnO-NR) mixed-dimensional heterostructure including the armchair ZnO nanoribbon (a-ZnO-NR) and zigzag ZnO nanoribbon (z-ZnO-NR) on WSe2 layer by using the first principles calculation. The results show that the binding strength of WSe2/ZnO-NR is enhanced. Remarkably, the WSe2/ZnO-NR presents anisotropic electronic properties under strain effect. Firstly, whether the WSe2/a-ZnO-NR is passivated by hydrogens or not, they always show type-I direct band gap alignment. After the strain applied, the band structures are transformed into type-II band alignment, promoting the separation of photogenerated electron-hole pairs. For WSe2/z-ZnO-NR, it exhibits type-II band alignment. The strain engineering can effectively modulate the band gap of WSe2/z-ZnO-NR. When the edge of z-ZnO-NR is not passivatied, the WSe2/z-ZnO-NR shows spin polarized band structure with a narrow gap. The band gap and spin polarization can be tuned by strain. The projected band structures reveal that the WSe2/z-ZnO-NR not only forms type-II band alignment, but also realizes the separation of different spin states. This work provides useful guide for designing photoelectronic devices experimentally.

In this paper, large-area graphene films composed of mono- and bi-layer have been successfully synthesized by atmospheric pressure chemical vapor deposition (CVD) on Cu foils using solid coronene as the carbon precursor. The number of graphene layers was precisely controlled by adjusting the growth temperature range. In addition, the hexagonal lattice of graphene was shown using Raman spectroscopy, transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The continuity and uniformity of graphene films were confirmed by optical microscopy and scanning electron microscopy (SEM). Further, the presence of weak localization was shown by magneto-transport measurements with the carrier mobility of 2120 cm2/Vs at room temperature. This solid-precursor-based atmospheric pressure CVD method provides a simple, inexpensive and safe route for fabrication of graphene films.

We report a nonenzymatic H2O2 sensor based on a glassy carbon electrode modified with bilayer graphene films (BGFs) that were decorated with well-defined Pd nanoparticles. The BGFs were synthesized with a chemical vapor deposition process, and the Pd nanoparticle films were produced by gas phase cluster beam deposition. The BGFs provide great accessible active surface area and excellent conductive interfaces for electron transfer, which largely enhance the electrocatalytic performance of the modified electrodes. A rapid response time of less than 3 s and a wide linear range from 4 μM to 13.5 mM was exhibited in the amperometric detection of H2O2.

The nonsequential double ionization (NSDI) of atom is revisited by elliptically polarized few-cycle laser pulse with the classical ensemble method. We focus on the events that both electrons emit into the same direction along the long and short axis of the laser polarization plane, and how do the correlated electron momentum spectra of these two events depends on the carrier-envelope-phase (CEP). We first exhibit that the double-ionization probability has a negligible dependence on CEP. Back analysis shows that the ionization dynamics of the second electron are strongly depend on the CEP, which is significantly responsible for the CEP-dependent correlated electron momentum spectra. Besides, the correlated electron momentum spectrum along the long axis of the laser polarization plane reproduces the so-called V-like structure (also called the figurelike structure) observed in experiments [A. Staudte, et al., Phys. Rev. Lett. 99, 263002 (2007); A. Rudenko, et al., Phys. Rev. Lett. 99, 263003 (2007)]. We sort the V-like shape into two regions and find that the different regions exhibit significantly different dynamics behaviors. Simultaneously, we demonstrate that the electron pairs emitted into the same direction along the short axis of the laser polarization plane is a result of the nuclear–electron attraction, and both the nuclear–electron attraction and e–e repulsion significantly contribute to the V-like structure.

In this work, the Pb(Zr0.2Ti0.8)O3/(La0.67Ca0.33)MnO3 heterostructure film is deposited on the Pt/Ti/SiO2/Si wafer. The dominant transport is the inelastic hopping conduction. Due to the interaction between ferroelectric domain and magnetic polaron, film still exhibits weak ferromagnetism above the Curie temperature. Under lower bias voltage, the non-zero sequential magnetoresistance occurs on the magnetic granular junction. As soon as bias voltage exceeds the coercive voltage, the ferroelectric domain is aligned, consequently the magnetoresistance tends to vanish. Such electric switch of magnetoresistance is potential for the electric-write magnetic-read storage device.

Graphene (Gr) has been demonstrated to be a two dimensional (2D) topological insulator (TI) with an opened spin–orbit coupling (SOC) energy gap at Dirac point. The extremely small energy gap, however, makes the predicted quantum spin Hall (QSH) effect difficult to be observed at room temperature. In present work, we propose an effective way to tune the energy gap of Gr by combining with GaSb. The intrinsic bulk gap of Gr reaches up to 125 meV and 116 meV in Gr/(Ga)Sb and Gr/Ga(Sb), respectively, which makes it available in practical applications. Moreover, the energy gap of Gr can be opened and increased to 147 meV in GaSb/Gr/GaSb by hydrogen passivation. The inverted band ordering and gapless edge states further demonstrate that our considered heterostructures possess QSH effect. Normal strain engineering leads to effective control and substantial enhancement of their energy gap and band inversion. Hexagonal boron nitride (h-BN) is also verified to be a suitable substrate to supporting films without destroying their QSH effect. Our results provide feasible platform to design Gr-based spintronics devices.

Indium selenide (InSe) is a promising two-dimensional photodetector material. However, band-gap and work-function of low-dimension InSe are too large to act as photodetector devices. Here, we design InSe-based vdWs heterostructure, InSe/hBN (hexagonal boron nitride), using first-principles. InSe/hBN possesses rather low work-function (~3.0 eV) compared with that of isolated InSe monolayer due to strong interlayer coupling. Besides, strong interlayer coupling induces extra emerging states, markedly reducing band-gap of InSe/hBN. Meanwhile, these emerging states ensure red-shift of optical absorption, from infrared to ultraviolet light-harvesting. Moreover, different heterostructure stacking mode doesn’t affect optical absorption and electron emission, convenient to the application of optoelectronics.

Summary Background Human infections with different avian influenza viruses—eg, H5N1, H9N2, and H7N9—have raised concerns about pandemic potential worldwide. We report the first human infection with a novel reassortant avian influenza A H10N8 virus. Methods We obtained and analysed clinical, epidemiological, and virological data from a patient from Nanchang City, China. Tracheal aspirate specimens were tested for influenza virus and other possible pathogens by RT-PCR, viral culture, and sequence analyses. A maximum likelihood phylogenetic tree was constructed. Findings A woman aged 73 years presented with fever and was admitted to hospital on Nov 30, 2013. She developed multiple organ failure and died 9 days after illness onset. A novel reassortant avian influenza A H10N8 virus was isolated from the tracheal aspirate specimen obtained from the patient 7 days after onset of illness. Sequence analyses revealed that all the genes of the virus were of avian origin, with six internal genes from avian influenza A H9N2 viruses. The aminoacid motif GlnSerGly at residues 226–228 of the haemagglutinin protein indicated avian-like receptor binding preference. A mixture of glutamic acid and lysine at residue 627 in PB2 protein—which is associated with mammalian adaptation—was detected in the original tracheal aspirate samples. The virus was sensitive to neuraminidase inhibitors. Sputum and blood cultures and deep sequencing analysis indicated no co-infection with bacteria or fungi. Epidemiological investigation established that the patient had visited a live poultry market 4 days before illness onset. Interpretation The novel reassortant H10N8 virus obtained is distinct from previously reported H10N8 viruses. The virus caused human infection and could have been associated with the death of a patient. Funding Emergency Research Project on human infection with avian influenza H7N9 virus, the National Basic Research Program of China, and the National Mega-projects for Infectious Diseases.

Density functional theory calculations on medium-sized GanAsm clusters (n + m = 17–24, n − m = 0, ±1) are reported. The total polarizabilities of GanAsm clusters exhibit a linear dependence on their volumes despite of different composition, giving a way to predict the polarizabilities of larger clusters. The polarizabilities are also strongly correlated to ionization potentials and composition. Isomerization may be the main reason why the even–odd oscillation of polarizabilities disappears in this size from experiment. Ultra stability of Ga9As10 and unusual electronic properties of Ga10As11 are found due to their special structures.

Few-layer graphene sheets were prepared by splitting expanded graphite using high-power sonication. Atomic-level calibrated scanning transmission electron microscopy was used to obtain efficient layer statistics, enabling optimization of the experimental conditions. This resulted in a two-step splitting mechanism in which the mean number of layers was first reduced to less than 20 by heating to 1100 °C and then to a few-layer region by a 5-min 104 W L−1 – power-density sonication. Raman spectroscopic analysis confirms the above mechanism and demonstrates that the sheets are largely free of defects and functional groups.

Well-defined Au nanoplates have been mass-synthesized through a chemical method at high and low temperatures. A time-saving method for the fabrication of hexagonal Au nanoplates has been developed by modifying polyol process with the presence of binary surfactants. In general methods, most Au nanoplates are in regular shapes of triangle and hexagon. While Au nanoplates with novel shapes, involving star-like and shield-like and other novel polygonal, are found with introduction of obvious temperature variation in the early crystal growth stage. Structural studies demonstrate that the obtained Au nanoplates are single-crystalline with (1 1 1) planes as two basal surfaces. The formation of these new and well-defined Au nanoplates can be understood from the growth of (1 1 1) plane along 〈1 1 0〉, 〈2 1 1〉 and other high-index directions. The ability to control the shape of Au nanoplates provides a great opportunity to systematically investigate the anisotropic growth of noble nanostructures.

The giant magnetostrictive Tb–Fe films assembled by nanoparticles have been prepared by the low energy cluster beam deposition. The dependence of the magnetostriction on the size of the nanoparticles is examined for the films. It is shown that the nanofilms have obtained higher saturation magnetostriction at the cluster size of 30 nm in average. The dependence of magnetostriction on particle size is ascribed to the degree of magnetic anisotropy which is related to the effective distance of exchange coupling between the adjacent Tb–Fe nanoparticles. This work demonstrates that the magnetostriction can be varied by tuning the particle size, which is important for control over the magnetostrictive properties of the films at nanoscale.

Cobalt doped ZnO film assembled by the nanoparticles was prepared by low energy cluster beam deposition. The microstructure, phase structure and optical properties were investigated for the nanostructured films. The results show that the nanostructured film was assembled by monodisperse spherical nanoparticles with average diameter of about 29.3 nm which are distributed uniformly and compactly. The results of X-ray diffraction (XRD) show that cobalt doped ZnO nanostructured film is indexed to a wurtzite structure of ZnO, and no Co-phase structure and other phases are observed. The UV-visible absorption spectra show that the optical band-gap of the film is broadened after doping.

The structure, electronic and magnetic properties of Si n Ni clusters up to n = 17 are systematically investigated using the density-functional theory (DFT) within the generalized gradient approximation (GGA). In the ground configurations of Si n Ni clusters, the equilibrium site of Ni atom gradually moves from convex, to a surface, and to a concave site as the number of Si atoms varying from 1 to 17. Starting from n = 8, the Ni atom completely falls into the center of the Si outer frame, forming Ni-encapsulated Si cages. Maximum peaks of second-order energy difference are found at n = 5, 7, 10, 12 and 14, indicating that these clusters possess relatively higher stability. Especially, Si 10 Ni cluster is more stable. The electronic structures and magnetic properties of Si n Ni clusters are discussed. The strong hybridization between Ni 4s, 3d, 4p and Si 3s, 3p states leads to the decrease of the gaps between highest-occupied and lowest-unoccupied molecular orbitals of Si n Ni clusters compared with corresponding those of Si n clusters and may be one of important factors which result in Si n Ni clusters magnetic moment quenched except for Si 2 Ni cluster.

Bilayer PVDF/Metglas laminates with remarkably anisotropic ME coupling effect have been fabricated. By a careful evaluation of these anisotropic behaviors both experimentally and theoretically, we demonstrate that an ultra-sensitive detection of weak dc magnetic field and its spatial orientation is practically applicable using the bilayer PVDF/Metglas laminate. This magnetic field probe has quite high sensitivity. The reason for such a high magnitude and orientation-dependent magnetoelectric coupling is explained. (C) 2009 Elsevier B.V. All rights reserved.

Dense Si nano-dots with a surface area density of >1010 cm−2 were fabricated by excimer laser induced crystallization of 15 nm-thick amorphous Si thin films. The enhanced electron field emission characteristics were found from laser irradiated samples. The threshold electric field is as low as 9.8V/μm and the field enhancement factor can reach as large as 719, which is compatible with the other good cold cathode materials. The improvements in field emission behavior can be associated with the change in the surface morphology after laser irradiation as well as the enhanced internal electric field due to the formation of Si nano-dots within the films.

Magnetoelectric CoFe2O4/Pb(Zr0.52Ti0.48)O3 composite nanotubes with diameters about 80 and 300 nm, and the length about 100 μm, were prepared by sol–gel template method. The studies with transmission electron microscopy (TEM) revealed that the composite material is characterized by the tubular microstructure; and X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns showed the coexistence of spinel CoFe2O4 (CFO) and perovskite Pb(Zr0.52Ti0.48)O3 (PZT) phases in the composite (CFO/PZT) nanotubes. Magnetic property of the CFO/PZT composite nanotubes was similar to pure CFO nanotubes. Also, the composite nanotubes exhibited ferroelectricity, which was just the same as the pure PZT nanotubes.

Amorphous BN films were prepared by the RF magnetron sputtering method and their field emission behaviors were characterized by I – V curves and F – N plots. Changes of electric field were carried out by increase/decrease in order to test the lifetime of the cascade material. In the meantime AFM and SEM monitored the change in the films’ morphologies and compositions. We find that the nano-sized islands can act as the FE emitters and essentially determine the FE performance of the films. We also report the existence of an activation process, after which the cascade performs more satisfactorily in higher emission current. It is also supposed that the field-induced evaporation plays an important role in the exhaust of the cascade material.

The magnetoelectric coupling effect in a bilayered magnetostrictive/piezoelectric composite structure consisting of a Tb0.3Dy0.7Fe1.9 layer bonded with a Pb(Zr0.52Ti0.48)O-3 layer is numerically simulated using the finite-element method. The numerical algorithm is based on a synchronization of the mechanical coupling and resonance between the two layers along the bonding interface. The magnetoelectric effect calculated as a function of the dimension of the two components, respectively, allows us to conclude that a significant enhancement of the magnetoelectric effect by optimizing the thickness of the two layers respectively is possible. (C) 2004 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Poly(N-vinyl-2-pyrrolidone) (PVP) cluster-assembled nanostructured films have been prepared by low energy cluster beam deposition method. TEM micrographs show that the films are assembled by spherical particles, which are distributed uniformly and randomly in the films. The pressure of helium carrier gas has a significant effect on the particle sizes and their distribution. Fourier transform infra-red and UV–Vis absorption spectra measurement have been performed so as to determine the structures and analyze the optical properties of the films. It is shown that the structural units of the nanoparticles of PVP cluster-assembled films are almost the same as that of original PVP. When compared to the original PVP casting film, PVP cluster-assembled film has 18 nm blue shift of maximum absorption and 0.67 eV blue shift of band gap.

The magnetoelectric coefficient of Ni 2 MnGa/PbZr 0.52 Ti 0.48 O 3 bi-layer structure as a function of temperature is measured. A distinct peak of the magnetoelectric coefficient was observed near the martensitic transition point of Ni 2 MnGa alloy. The value of this peak is 6–7 times larger than the others at room temperature. The origin of the peak and the relation between the magnetoelectric peak and the martensitic transition is discussed.