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

Quasi freestanding graphene on SiC 0001 via cobalt intercalation of zero layer graphene

Modification of the electronic and crystal structure of zero layer graphene grown on 6H SiC 0001 after Co intercalation is reported. Using a wide range of techniques including angle resolved photoelectron spectroscopy, x ray photoelectron spectroscopy, Raman spectroscopy, low energy electron diffraction, we found that zero layer graphene on SiC transforms into graphene monolayer as a result of cobalt intercalation. The Dirac cone of amp; 960; band characteristic of quasi freestanding graphene is observed. In combination with high resolution transmission electron microscopy and atomic force microscopy data, we conclude that ultrathin silicide CoSi CoSi2 structure is formed between graphene and SiC substrate. Investigation of magnetic properties reveals ferromagnetic behavior with open hysteresis loop. The results of this work are the basis for further implementation of magneto spin orbit graphene on a semiconducting substrate and are important for the future application of such graphene in spintronic

The Rare Decay B→K∗γB\to K^{\ast}\gamma: A More Precise Calculation

Efforts to predict the rare exclusive decay $B\to K^{\ast}\gamma$ from the well known inclusive decay $b\to s\gamma$ are frustrated by the effect of the large recoil momentum. We show how to reduce the large uncertainty in calculating this decay by relating $B\to K^{\ast}\gamma$ to the semileptonic process $B\to\rho e\bar{\nu}$ using the heavy-quark symmetry in B decays and SU(3) flavor symmetry. A direct measurement of the $q^{2}$-spectrum for the semileptonic decay can provide accurate information for the exclusive rare decay.Comment: 15 pages, UTPT-93-02, in REVTEX with one figure in ep

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Searches for new physics by the CMS collaboration are interpreted in the framework of the phenomenological minimal supersymmetric standard model (pMSSM). The data samples used in this study were collected at root s = 7 and 8 TeV and have integrated luminosities of 5.0 fb(-1) and 19.5 fb(-1), respectively. A global Bayesian analysis is performed, incorporating results from a broad range of CMS supersymmetry searches, as well as constraints from other experiments. Because the pMSSM incorporates several well-motivated assumptions that reduce the 120 parameters of the MSSM to just 19 parameters defined at the electroweak scale, it is possible to assess the results of the study in a relatively straightforward way. Approximately half of the model points in a potentially accessible subspace of the pMSSM are excluded, including all pMSSM model points with a gluino mass below 500 GeV, as well as models with a squark mass less than 300 GeV. Models with chargino and neutralino masses below 200 GeV are disfavored, but no mass range of model points can be ruled out based on the analyses considered. The nonexcluded regions in the pMSSM parameter space are characterized in terms of physical processes and key observables, and implications for future searches are discussed

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The algorithm developed by the CMS Collaboration to reconstruct and identify τ leptons produced in proton-proton collisions at √s=7 and 8 TeV, via their decays to hadrons and a neutrino, has been significantly improved. The changes include a revised reconstruction of π⁰ candidates, and improvements in multivariate discriminants to separate τ leptons from jets and electrons. The algorithm is extended to reconstruct τ leptons in highly Lorentz-boosted pair production, and in the high-level trigger. The performance of the algorithm is studied using proton-proton collisions recorded during 2016 at √s=13 TeV, corresponding to an integrated luminosity of 35.9 fb¯¹. The performance is evaluated in terms of the efficiency for a genuine τ lepton to pass the identification criteria and of the probabilities for jets, electrons, and muons to be misidentified as τ leptons. The results are found to be very close to those expected from Monte Carlo simulation

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