959 research outputs found

    Financial Crises: Lessons from History for Today

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    Cataloged from PDF version of article.Making use of the propensity score matching method, we match earlier crises (pre-2007) with currently ongoing crises (post-2007). The old and new crises are matched in three dimensions: the global setting in which they occurred, the structure of the economy and the domestic vulnerabilities in the pre-crisis period. Our findings suggest that the euro periphery crises share sufficient commonalities with earlier crises in their pre-crisis domestic vulnerabilities. The study points to two important conclusions. First, the euro periphery crises are composed of unique country experiences; hence, it will not be easily resolved with a 'one-size-fits-all' set of economic policies. Secondly, while each banking crisis has its inherent uniqueness, each crisis also shares sufficient commonalities with one or more of the Asian-5 1996/97 crises, the Nordic banking crisis of the early 1990s or the Japanese banking crisis of the 1990s. Thus, the extensive knowledge accumulated through these former banking crises can help in designing recovery policies

    FMR Study of Co/Ti Bilayer Thin Films

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    . We focused on the interaction between two ferromagnetic cobalt layers through a non-magnetic titanium layer. The magnetic properties of the structure were characterized by ferromagnetic resonance technique (FMR). The data were collected as a function of non-magnetic titanium layer thickness. Co/Ti multilayer (Ti (50 {\AA})/Co(45 {\AA})/Ti(2-40 {\AA})/Co(40 {\AA})/Ti(100 {\AA}))films were grown onto naturally oxidized p-type single crystal Si (100) substrate at UHV condition with magnetron sputtering system at room temperature. The thickness of Ti spacer layer ranges from 2 to 40 {\AA} with 2 {\AA} steps. We did not observe usual optic and acoustic modes; instead we had two broad overlapped peaks for the films ranged from 6 {\AA} to 40 {\AA}. One interesting result was the high anisotropic resonance field values for these films. Exchange coupling between ferromagnetic layers causes shift on resonance field values but these shifts in our samples were much larger than expected. This large anisotropic behavior is not clear at the moment. Our theoretical model was not able to determine a value for the exchange coupling parameter. One reason can be the close thickness values for Co sublayers. The other reason can be the Ti non-magnetic layer. If titanium did not grow layer by layer on cobalt, the cobalt ferromagnetic layers may behave as a single layer. As a result one cannot observe exchange interaction between ferromagnetic layers through non-magnetic spacer.Comment: 6 pages, 5 figure

    Topological surface transport in epitaxial SnTe thin films grown on Bi₂Te₃

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    The topological crystalline insulator SnTe has been grown epitaxially on a Bi₂Te₃ buffer layer by molecular beam epitaxy. In a 30-nm-thick SnTe film, p- and n-type carriers are found to coexist, and Shubnikov–de Haas oscillation data suggest that the n-type carriers are Dirac fermions residing on the SnTe (111) surface. This transport observation of the topological surface state in a p-type topological crystalline insulator became possible due to a downward band bending on the free SnTe surface, which appears to be of intrinsic origin

    Room-temperature ferromagnetism in Sr_(1-x)Y_xCoO_(3-delta) (0.2 < x < 0.25)

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    We have measured magnetic susceptibility and resistivity of Sr1x_{1-x}Yx_xCoO3δ_{3-\delta} (x=x= 0.1, 0.15, 0.2, 0.215, 0.225, 0.25, 0.3, and 0.4), and have found that Sr1x_{1-x}Yx_xCoO3δ_{3-\delta} is a room temperature ferromagnet with a Curie temperature of 335 K in a narrow compositional range of 0.2 x\leq x\leq 0.25. This is the highest transition temperature among perovskite Co oxides. The saturation magnetization for x=x= 0.225 is 0.25 μB\mu_B/Co at 10 K, which implies that the observed ferromagnetism is a bulk effect. We attribute this ferromagnetism to a peculiar Sr/Y ordering.Comment: 5 pages, 4 figure

    Topological crystalline insulator states in Pb(1-x)Sn(x)Se

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    Topological insulators are a novel class of quantum materials in which time-reversal symmetry, relativistic (spin-orbit) effects and an inverted band structure result in electronic metallic states on the surfaces of bulk crystals. These helical states exhibit a Dirac-like energy dispersion across the bulk bandgap, and they are topologically protected. Recent theoretical proposals have suggested the existence of topological crystalline insulators, a novel class of topological insulators in which crystalline symmetry replaces the role of time-reversal symmetry in topological protection [1,2]. In this study, we show that the narrow-gap semiconductor Pb(1-x)Sn(x)Se is a topological crystalline insulator for x=0.23. Temperature-dependent magnetotransport measurements and angle-resolved photoelectron spectroscopy demonstrate that the material undergoes a temperature-driven topological phase transition from a trivial insulator to a topological crystalline insulator. These experimental findings add a new class to the family of topological insulators. We expect these results to be the beginning of both a considerable body of additional research on topological crystalline insulators as well as detailed studies of topological phase transitions.Comment: v2: published revised manuscript (6 pages, 3 figures) and supplementary information (5 pages, 8 figures

    Synchronization of multi-phase oscillators: An Axelrod-inspired model

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    Inspired by Axelrod's model of culture dissemination, we introduce and analyze a model for a population of coupled oscillators where different levels of synchronization can be assimilated to different degrees of cultural organization. The state of each oscillator is represented by a set of phases, and the interaction --which occurs between homologous phases-- is weighted by a decreasing function of the distance between individual states. Both ordered arrays and random networks are considered. We find that the transition between synchronization and incoherent behaviour is mediated by a clustering regime with rich organizational structure, where some of the phases of a given oscillator can be synchronized to a certain cluster, while its other phases are synchronized to different clusters.Comment: 6 pages, 5 figure

    Quantum magneto-optics of graphite family

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    The optical conductivity of graphene, bilayer graphene, and graphite in quantizing magnetic fields is studied. Both dynamical conductivities, longitudinal and Hall's, are analytically evaluated. The conductivity peaks are explained in terms of electron transitions. We have shown that trigonal warping can be considered within the perturbation theory for strong magnetic fields larger than 1 T and in the semiclassical approach for weak fields when the Fermi energy is much larger than the cyclotron frequency. The main optical transitions obey the selection rule with \Deltan = 1 for the Landau number n, however the \Deltan = 2 transitions due to the trigonal warping are also possible. The Faraday/Kerr rotation and light transmission/reflection in the quantizing magnetic fields are calculated. Parameters of the Slonczewski-Weiss-McClure model are used in the fit taking into account the previous dHvA measurements and correcting some of them for the case of strong magnetic fields.Comment: 28 pages, 12 figures. arXiv admin note: text overlap with arXiv:1106.340
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