Effects Of A Nearby Mn Delta Layer On The Optical Properties Of An Ingaas/gaas Quantum Well

We investigated the effects of nearby Mn ions on the confined states of a InGaAs/GaAs quantum well through circularly polarized and magneto-optical measurements. The addition of a Mn delta-doping layer at the barrier close to the well gives rise to surprisingly narrow absorption peaks in the photoluminescence excitation spectra. The peaks become increasingly stronger for decreasing spacer-layer thicknesses between the quantum well and the Mn layer. Most of the peaks were identified based on self-consistent calculations; however, we observed additional peaks that cannot be identified with quantum well transitions, which origin we attribute to an enhanced exciton-phonon coupling. Finally, we discuss possible effects related to the exciton magneto-polaron complex in the reinforcement of the photoluminescence excitation peaks.11620Žutić, I., Fabian, J., Sarma, S.D., (2004) Rev. Mod. Phys., 76, p. 323Dielt, T., Ohno, H., (2014) Rev. Mod. Phys., 86, p. 187Tanaka, M., Ohya, S., Hai, P.N., (2014) Appl. Phys. Rev., 1, p. 011102Krebs, O., Benjamin, E., Lemaître, A., (2009) Phys. Rev. B, 80, p. 165315Gazoto, A.L., Brasil, M.J.S.P., Iikawa, F., Brum, J.A., Ribeiro, E., Danilov, Y.A., Vikhrova, O.V., Zvonkov, B.N., (2011) Appl. Phys. Lett., 98, p. 251901Ohno, H., (1998) Science, 281, p. 951Nazmul, A.M., Amemiya, T., Shuto, Y., Sugahara, S., Tanaka, M., (2005) Phys. Rev. Lett., 95, p. 017201Korenev, V.L., Akimov, I.A., Zaitsev, S.V., Sapega, V.F., Langer, L., Yakovlev, D.R., Danilov, Y.A., Bayer, M., (2012) Nat. Commun., 3, p. 959Bobrov, A.I., Vikhrova, O.V., Danilov, Y.A., Dorokhin, M.V., Drozdov, Y.N., Drozdov, M.N., Zvonkov, B.N., Pavlova, E.D., (2014) Bull. Russ. Acad. Sci. Phys., 78 (1), pp. 6-8Wurstbauer, U., Soda, M., Jakiela, R., Schuh, D., Weiss, D., Zweck, J., Wegscheider, W., (2009) J. Cryst. Growth, 311 (7), p. 2160Poggio, M., Myers, R.C., Stern, N.P., Gossard, A.C., Awschalom, D.D., (2005) Phys. Rev. B, 72, p. 235313Balanta, M.A.G., Brasil, M.J.S.P., Iikawa, F., Mendes, U.C., Brum, J.A., Maialle, M.Z., Danilov, Y.A., Zvonkov, B.N., (2013) J. Phys. D: Appl. Phys., 46, p. 215103Lee, K.-S., Lee, C.-D., Kim, Y., Noh, S.K., (2003) Solid State Commun., 128, p. 177Hou, H.Q., Staguhn, W., Takeyama, S., Miura, N., Segawa, Y., Aoyagi, Y., Namba, S., (1991) Phys. Rev. B, 43, p. 4152Wu, J.-W., Nurmikko, A.V., Quinn, J.J., (1986) Phys. Rev. B, 34, p. 1080(1986) Solid State Commun., 57, p. 853Gonc¸alves Da Silva, C.E.T., (1985) Phys. Rev. B, 32, p. 6962Zhang, X.-C., Chang, S.-K., Nurmikko, A.V., Kolodziejski, L.A., Gunshor, R.L., Datta, S., (1985) Phys. Rev. B, 31, p. 4056Zhang, X.-C., Chang, S.-K., Nurmikko, A.V., Kolodziejski, L.A., Gunshor, R.L., Datta, S., (1985) Solid State Commun., 56, p. 255Zhang, X.-C., Chang, S.-K., Nurmikko, A.V., Kolodziejski, L.A., Gunshor, R.L., Datta, S., (1985) Appl. Phys. Lett., 47, p. 59Yakovlev, D.R., Ossau, W., (2010) Introduction to the Physics of Diluted Magnetic Semiconductors, p. 221. , edited by J. Kosut and J. A. Gaj Springer, Chap. 7Preisler, V., Grange, T., Ferreira, R., De Vaulchier, L.A., Guldner, Y., Teran, F.J., Potemski, M., Lemaitre, A., (2006) Phys. Rev. B, 73, p. 075320Verzelen, O., Bastard, G., Ferreira, R., (2000) Phys. Rev. B, 62, p. R4809Verzelen, O., Bastard, G., Ferreira, R., (2002) Phys. Rev. B, 66, p. 081308RDickmann, S., Tartakovskii, A.I., Timofeev, V.B., Zhilin, V.M., Zeman, J., Martinez, G., Hvam, J.M., (2000) Phys. Rev. B, 62, p. 2743Lucovsky, G., Chen, M.F., (1970) Solid State Commun., 8, pp. 1397-140

Photoproduction of D∗±D^{*\pm} mesons associated with a leading neutron

The photoproduction of $D^{*\pm} (2010)$ mesons associated with a leading neutron has been observed with the ZEUS detector in $ep$ collisions at HERA using an integrated luminosity of 80 pb$^{-1}$. The neutron carries a large fraction, {$x_L>0.2$}, of the incoming proton beam energy and is detected at very small production angles, {$\theta_n<0.8$ mrad}, an indication of peripheral scattering. The $D^*$ meson is centrally produced with pseudorapidity {$|\eta| 1.9$ GeV}, which is large compared to the average transverse momentum of the neutron of 0.22 GeV. The ratio of neutron-tagged to inclusive $D^*$ production is $8.85\pm 0.93({\rm stat.})^{+0.48}_{-0.61}({\rm syst.})\%$ in the photon-proton center-of-mass energy range {$130 <W<280$ GeV}. The data suggest that the presence of a hard scale enhances the fraction of events with a leading neutron in the final state.Comment: 28 pages, 4 figures, 2 table

Measurement of the open-charm contribution to the diffractive proton structure function

Production of D*+/-(2010) mesons in diffractive deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 82 pb^{-1}. Diffractive events were identified by the presence of a large rapidity gap in the final state. Differential cross sections have been measured in the kinematic region 1.5 < Q^2 < 200 GeV^2, 0.02 < y < 0.7, x_{IP} < 0.035, beta 1.5 GeV and |\eta(D*+/-)| < 1.5. The measured cross sections are compared to theoretical predictions. The results are presented in terms of the open-charm contribution to the diffractive proton structure function. The data demonstrate a strong sensitivity to the diffractive parton densities.Comment: 35 pages, 11 figures, 6 table

Isolated tau leptons in events with large missing transverse momentum at HERA

A search for events containing isolated tau leptons and large missing transverse momentum, not originating from the tau decay, has been performed with the ZEUS detector at the electron-proton collider HERA, using 130 pb^-1 of integrated luminosity. A search was made for isolated tracks coming from hadronic tau decays. Observables based on the internal jet structure were exploited to discriminate between tau decays and quark- or gluon-induced jets. Three tau candidates were found, while 0.40 +0.12 -0.13 were expected from Standard Model processes, such as charged current deep inelastic scattering and single W-boson production. To search for heavy-particle decays, a more restrictive selection was applied to isolate tau leptons produced together with a hadronic final state with high transverse momentum. Two candidate events survive, while 0.20 +-0.05 events are expected from Standard Model processes.Comment: 28 pages, 4 figures, 3 tables, accepted by Phys. Lett. B. Updated with minor changes to the text requested by the journal refere

Search for contact interactions, large extra dimensions and finite quark radius in ep collisions at HERA

A search for physics beyond the Standard Model has been performed with high-Q^2 neutral current deep inelastic scattering events recorded with the ZEUS detector at HERA. Two data sets, e^+ p \to e^+ X and e^- p \to e^- X, with respective integrated luminosities of 112 pb^-1 and 16 pb^-1, were analyzed. The data reach Q^2 values as high as 40000 GeV^2. No significant deviations from Standard Model predictions were observed. Limits were derived on the effective mass scale in eeqq contact interactions, the ratio of leptoquark mass to the Yukawa coupling for heavy leptoquark models and the mass scale parameter in models with large extra dimensions. The limit on the quark charge radius, in the classical form factor approximation, is 0.85 10^-16 cm.Comment: 28 pages, 4 figures, accepted for publication in Physics Letters

Analysis of new approaches to identifying risks and ensuring financial stability in modern national financial systems

This paper explores new approaches to identifying financial stability risks and implementing financial stability policies in the contemporary national financial systems. The need for new approaches is primarily explained by a dramatic expansion of the range of financial stability risks due to the increasingly important role of non-banking financial institutions and financial markets in the operation of financial systems, as well as the growing financial inclusion of firms and households. The problems of assessing financial stability are given a special focus. Based on the analysis of financial stability metrics used by the world&rsquo;s leading central banks and recommended by international financial organizations, the authors formulate proposals for modernizing the system of financial stability indicators used by the Bank of Russia. We formulated proposals on measures to protect the domestic market from external shocks arising from changes in the monetary policy conducted by the world&rsquo;s leading central banks; on accounting for the expanded range of financial stability risks; and on harmonizing financial stability policies with other areas of financial development

Contemporary working conditions and assessment of occupational health risk for workers employed at flour-grinding productions

The paper gives a complex hygienic characteristics of working conditions at typical contemporary flour-grinding productions which deal with grain processing. It is shown that workers who are employed at flour-grinding production and perform their work tasks at all the stages of technological cycle on grain processing are exposed to a set of adverse industrial factors related to their labor process. These factors create hazardous working conditions which are ranked as having the 2nd and the 3rd hazard degree (3.2 and 3.3 categories) as per the Guide Р 2.2.2006-05. Among primary factors which create hazardous working conditions we can mention flour dust; grain dust; industrial noise; adverse microclimate; labor hardness caused by overall high physical dynamic loads borne by arms, body, and legs; a necessity to stay in an inconvenient and forced working posture; constant moving related to maintenance of equipment and control over production processes. According to the Guide Р 2.2.1766-03, categories of expected occupational health risk for workers are estimated to vary from average (substantial) risk to high (intolerable) one depending on functions performed by a worker. Working area air con-tamination with grain dust and flour dust are considered to be a priority health risk factor for workers employed at flour-grinding production. As we assessed occupational risks as per data obtained during periodical medical examinations, we detected an average authentic cause-and-effect relationship between working conditions factors and respiratory organs diseases (RR = 1.64; EF = 39 %, CI = 0.5–4.5), which meant such diseases were occupationally induced. Basing on the performed research, we developed priority measures which can help to reduce occupational health risks for workers employed at flour-grinding production

Abies sawdust delignification by CH3COOH/H2O2 mixture in the presence of TiO2 catalyst

Note: 398

Pure spin currents induced by spin-dependent scattering processes in SiGe quantum well structures

We show that spin-dependent electron-phonon interaction in the energy relaxation of a two-dimensional electron gas results in equal and oppositely directed currents in the spin-up and spin-down subbands yielding a pure spin current. In our experiments on SiGe heterostructures the pure spin current is converted into an electric current applying a magnetic field that lifts the cancellation of the two partial charge flows. A microscopic theory of this effect, taking account of the asymmetry of the relaxation process, is developed and is in good agreement with the experimental data