Magnetic mixed valent semimetal EuZnSb2_2 with Dirac states in the band structure

We report discovery of new antiferromagnetic semimetal EuZnSb$_2$, obtained and studied in the form of single crystals. Electric resistivity, magnetic susceptibility and heat capacity indicate antiferromagnetic order of Eu with $T_N$ = 20 K. The effective moment of Eu$^{2+}$ inferred from the magnetization and specific heat measurement is 3.5 $\mu_B$, smaller than the theoretical value of Eu$^{2+}$ due to presence of both Eu$^{3+}$ and Eu$^{2+}$. Magnetic field-dependent resistivity measurements suggest dominant quasi two dimensional Fermi surfaces whereas the first-principle calculations point to the presence of Dirac fermions. Therefore, EuZnSb$_2$ could represent the first platform to study the interplay of dynamical charge fluctuations, localized magnetic 4$f$ moments and Dirac states with Sb orbital character.Comment: 9 pages, 4 figure

Robust method for broadband efficiency enhancement of electron photocathodes using optical interferences

We demonstrate the key features of an interference cathode using both simulations and experiments. We deposit Cs3Sb photocathodes on Ag to produce an interference enhanced photocathode with 2 5 quantum efficiency QE enhancement using a robust procedure that requires only a smooth metal substrate and QE monitoring during growth. We grow both an interference cathode Ag substrate and a typical photocathode Si reference substrate simultaneously to confirm that the effects are due to optical interactions with the substrate rather than photocathode composition or surface electron affinity differences. Growing the cathodes until the QE converges shows both the characteristic interference peaks during growth and the identical limiting case where the cathode is infinitely thick, in agreement with simulations. We also grow a cathode until the QE on Ag peaks and then stop the growth, demonstrating broadband QE enhancemen

Operando spectroscopy study of the carbon dioxide electro-reduction by iron species on nitrogen-doped carbon

The carbon–carbon coupling via electrochemical reduction of carbon dioxide represents the biggest challenge for using this route as platform for chemicals synthesis. Here we show that nanostructured iron (III) oxyhydroxide on nitrogen-doped carbon enables high Faraday efficiency (97.4%) and selectivity to acetic acid (61%) at very-low potential (−0.5 V vs silver/silver chloride). Using a combination of electron microscopy, operando X-ray spectroscopy techniques and density functional theory simulations, we correlate the activity to acetic acid at this potential to the formation of nitrogen-coordinated iron (II) sites as single atoms or polyatomic species at the interface between iron oxyhydroxide and the nitrogen-doped carbon. The evolution of hydrogen is correlated to the formation of metallic iron and observed as dominant reaction path over iron oxyhydroxide on oxygen-doped carbon in the overall range of negative potential investigated, whereas over iron oxyhydroxide on nitrogen-doped carbon it becomes important only at more negative potentials

Spin canting across core/shell Fe3O4/MnxFe3−xO4 nanoparticles

Magnetic nanoparticles (MNPs) have become increasingly important in biomedical applications like magnetic imaging and hyperthermia based cancer treatment. Understanding their magnetic spin configurations is important for optimizing these applications. The measured magnetization of MNPs can be significantly lower than bulk counterparts, often due to canted spins. This has previously been presumed to be a surface effect, where reduced exchange allows spins closest to the nanoparticle surface to deviate locally from collinear structures. We demonstrate that intraparticle effects can induce spin canting throughout a MNP via the Dzyaloshinskii-Moriya interaction (DMI). We study ~7.4 nm diameter, core/shell Fe3O4/MnxFe3−xO4 MNPs with a 0.5 nm Mn-ferrite shell. Mössbauer spectroscopy, x-ray absorption spectroscopy and x-ray magnetic circular dichroism are used to determine chemical structure of core and shell. Polarized small angle neutron scattering shows parallel and perpendicular magnetic correlations, suggesting multiparticle coherent spin canting in an applied field. Atomistic simulations reveal the underlying mechanism of the observed spin canting. These show that strong DMI can lead to magnetic frustration within the shell and cause canting of the net particle moment. These results illuminate how core/shell nanoparticle systems can be engineered for spin canting across the whole of the particle, rather than solely at the surface

Організаційно-економічне забезпечення розвитку електронної промисловості

Розкрито питання організаційно-економічного забезпечення електронної промисловості в рамках організаційно-економічного механізму розвитку електронної промисловості на інноваційній основі, який регламентує діяльність державних, галузевих і підприємницьких структур, що забезпечують розвиток електронної промисловості. Ключові слова: електронна промисловість, організаційне забезпечення розвитку електронної промисловості, організаційно-економічний механізм, інноваційний розвиток.  Раскрываются вопросы организационно-экономического обеспечения электронной промышленности в рамках организационно-экономического механизма развития электронной промышленности на инновационной основе, который регламентирует деятельность государственных, отраслевых и предпринимательских структур, обеспечивающих развитие электронной промышленности. Ключевые слова: электронная промышленность, организационное обеспечение развития электронной промышленности, организационно-экономический механизм, инновационное развитие.  The paper deals with the issues of organizational and economic support of electronic industry in the framework of the organizational and economic mechanism of the above industry development on the basis of innovation. It regulates the activities of the government, sectoral and business organizations, which provide the development of the electronic industry. The proposalsare as follows: to work out a State Program of Development of the Electronic Industry, andto create a sectoral information system, a cluster “development of the electronic industry”, holding the electronic industry, a sectoral technology transfer system, training educational and scientific centres for the engineering staff. It is shown that at a corporate level the development of electronic industry is promoted by establishment of production facilities with the use of well-known brands and foreign electronic productions, technologies transfer with consideration of supply channels, introduction of business market mechanisms, IPC standards, and production information systems PDM/PLM. A specific feature of these measures is that to develop the issues of financial and economic, technical and technological, innovation and market support of the electronic industry development the methods of grouping, generalization of economic indicators received from the enterprises of this industry, and economic mathematical modelling using a correlation regression and structural logical analysis have been used. The application of these methods suggests that the use of the organizational and economic support contributes to promising development of the electronic industry in Ukraine which consists in formation of the core of the electronic industry and its integration in the world electronic space in the future. Keywords: electronic industry, organizational support of electronic industry development, organizational and economic mechanism, innovation-based development

Measurement of inclusive π0\pi^{0} production in hadronic Z0Z^{0} decays

An analysis is presented of inclusive \pi^0 production in Z^0 decays measured with the DELPHI detector. At low energies, \pi^0 decays are reconstructed by \linebreak using pairs of converted photons and combinations of converted photons and photons reconstructed in the barrel electromagnetic calorimeter (HPC). At high energies (up to x_p = 2 \cdot p_{\pi}/\sqrt{s} = 0.75) the excellent granularity of the HPC is exploited to search for two-photon substructures in single showers. The inclusive differential cross section is measured as a function of energy for {q\overline q} and {b \bar b} events. The number of \pi^0's per hadronic Z^0 event is N(\pi^0)/ Z_{had}^0 = 9.2 \pm 0.2 \mbox{(stat)} \pm 1.0 \mbox{(syst)} and for {b \bar b}~events the number of \pi^0's is {\mathrm N(\pi^0)/ b \overline b} = 10.1 \pm 0.4 \mbox{(stat)} \pm 1.1 \mbox{(syst)} . The ratio of the number of \pi^0's in b \overline b events to hadronic Z^0 events is less affected by the systematic errors and is found to be 1.09 \pm 0.05 \pm 0.01. The measured \pi^0 cross sections are compared with the predictions of different parton shower models. For hadronic events, the peak position in the \mathrm \xi_p = \ln(1/x_p) distribution is \xi_p^{\star} = 3.90^{+0.24}_{-0.14}. The average number of \pi^0's from the decay of primary \mathrm B hadrons is found to be {\mathrm N} (B \rightarrow \pi^0 \, X)/\mbox{B hadron} = 2.78 \pm 0.15 \mbox{(stat)} \pm 0.60 \mbox{(syst)}

Search for new phenomena using single photon events in the DELPHI detector at LEP

Data are presented on the reaction \epem~\into~\gamma + no other detected particle at center-of-mass energies, \sqs = 89.48 GeV, 91.26 GeV and 93.08 GeV. The cross section for this reaction is related directly to the number of light neutrino generations which couple to the \zz boson, and to several other phenomena such as excited neutrinos, the production of an invisible `X' particle, a possible magnetic moment of the tau neutrino, and neutral monojets. Based on the observed number of single photon events, the number of light neutrinos which couple to the \zz is measured to be N_\nu = 3.15 \pm 0.34. No evidence is found for anomalous production of energetic single photons, and upper limits at the 95\% confidence level are determined for excited neutrino production (BR < 4-9 \times 10^{-6}), production of an invisible `X' particle (\sigma < 0.1 pb), and the magnetic moment of the tau neutrino (< 5.2 \times 10^{-6} \mu_B). No event with the topology of a neutral monojet is found, and this corresponds to the limit \sigma < 0.044/\epsilon pb at the 95\% confidence level, where \epsilon is the unknown overall monojet detection efficiency

Measurement of the Bd0^{0}_{d} oscillation frequency using kaons, leptons and jet charge

A measurement of the mass difference, \Delta m_d, between the two physical \mbox{B}^0_d states has been obtained from the analysis of the impact parameter distribution of a lepton emitted at large transverse momentum (p_t) relative to the jet axis and from the analysis of the flight distance distribution of secondary vertices tagged by either a high p_t lepton or an identified kaon. In the opposite hemisphere of the event, the charge of the initial quark has been evaluated using a high p_t lepton, a charged kaon or the mean jet charge. With 1.7 million hadronic Z^0 decays recorded by DELPHI between 1991 and 1993, \Delta m_d is found to be: \Delta m_d = 0.531^{+0.050}_{-0.046} ~(stat.) \pm 0.078 ~(syst.) ~ {\mathrm{ps}}^{-1} \,