485 research outputs found

    Rejecting Collective Bargaining Agreements Under Section 1113 of the Bankruptcy Code - Judicial Precision or Economic Reality?

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    Before a Chapter 11 debtor in possession can reject the collective bargaining agreement, section 1113 of the Bankruptcy Code requires it to bargain with the representative of its employees and then obtain court approval. Because Congress sought to accommodate the interests of both organized labor and the business community, section 1113 contains numerous terms of compromise which ultimately are interpreted by the courts. The authors have reviewed the major litigation, and have suggested trends in the judicial interpretation of section 1113. However, rejection of collective bargaining litigation is counterproductive with respect to Chapter 11 reorganizations. Rather, the authors believe that the debtor and the union should focus on the economical reality of their situation, rather than the strength of their respective legal positions, to reach agreement at the bargaining table and avoid contract rejection litigation

    Evidence of a universal and isotropic 2\Delta/kBTC ratio in 122-type iron pnictide superconductors over a wide doping range

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    We have systematically investigated the doping and the directional dependence of the gap structure in the 122-type iron pnictide superconductors by point contact Andreev reflection spectroscopy. The studies were performed on single crystals of Ba1-xKxFe2As2 (x = 0.29, 0.49, and 0.77) and SrFe1.74Co0.26As2 with a sharp tip of Pb or Au pressed along the c-axis or the ab-plane direction. The conductance spectra obtained on highly transparent contacts clearly show evidence of a robust superconducting gap. The normalized curves can be well described by the Blonder-Tinkham-Klapwijk model with a lifetime broadening. The determined gap value scales very well with the transition temperature, giving the 2{\Delta}/kBTC value of ~ 3.1. The results suggest the presence of a universal coupling behavior in this class of iron pnictides over a broad doping range and independent of the sign of the doping. Moreover, conductance spectra obtained on c-axis junctions and ab-plane junctions indicate that the observed gap is isotropic in these superconductors

    Superconductivity at 23 K in Pt doped BaFe2As2 single crystals

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    We report superconductivity in single crystals of the new iron-pnictide system BaFe1.9Pt0.1As2 grown by a self-flux solution method and characterized via x-ray, transport, magnetic and thermodynamic measurements. The magnetic ordering associated with a structural transition at 140 K present in BaFe2As2 is completely suppressed by substitution of 5% Fe with Pt and superconductivity is induced at a critical temperature Tc=23 K. Full diamagnetic screening in the magnetic susceptibility and a jump in the specific heat at Tc confirm the bulk nature of the superconducting phase. All properties of the superconducting state including transition temperature Tc, the lower critical field Hc1=200 mT, upper critical field Hc2~65 T, and the slope dHc2/dT are comparable in value to the those found in other transition-metal-substituted BaFe2As2 series, indicating the robust nature of superconductivity induced by substitution of Group VIII elements.Comment: 6 pgs, 4 figs, and 1 tbl, slightly revised, updated reference

    Quantum critical scaling at the edge of Fermi liquid stability in a cuprate superconductor

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    In the high temperature cuprate superconductors, the pervasiveness of anomalous electronic transport properties suggests that violation of conventional Fermi liquid behavior is closely tied to superconductivity. In other classes of unconventional superconductors, atypical transport is well correlated with proximity to a quantum critical point, but the relative importance of quantum criticality in the cuprates remains uncertain. Here we identify quantum critical scaling in the electron-doped cuprate material La2-xCexCuO4 with a line of quantum critical points that surrounds the superconducting phase as a function of magnetic field and charge doping. This zero-temperature phase boundary, which delineates a metallic Fermi liquid regime from an extended non-Fermi liquid ground state, closely follows the upper critical field of the overdoped superconducting phase and gives rise to an expanse of distinct non Fermi liquid behavior at finite temperatures. Together with signatures of two distinct flavors of quantum fluctuations, this suggests that quantum criticality plays a significant role in shaping the anomalous properties of the cuprate phase diagram.Comment: 16 pages, 3 figures + supplementary materia

    Josephson effect between electron-doped and hole-doped iron pnictide single crystals

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    We have observed the Josephson effect in junctions formed between single crystals of SrFe1.74Co0.26As2 and Ba0.23K0.77Fe2As2. The ac Josephson effect was observed under microwave irradiation in the I-V characteristics. By applying an in-plane magnetic field, the critical current is completely modulated and shows a relatively symmetric diffraction pattern consistent with the intermediate junction limit. The observation of the Josephson effect in the p-n bicrystal structure not only has significant implications for designing phase-sensitive junctions to probe the pairing symmetry of iron pnictide superconductors, but also represents an important step in developing all iron pnictide devices for applications.open252

    High pressure transport properties of the topological insulator Bi2Se3

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    We report x-ray diffraction, electrical resistivity, and magnetoresistance measurements on Bi2Se3 under high pressure and low temperature conditions. Pressure induces profound changes in both the room temperature value of the electrical resistivity as well as the temperature dependence of the resistivity. Initially, pressure drives Bi2Se3 towards increasingly insulating behavior and then, at higher pressures, the sample appears to enter a fully metallic state coincident with a change in the crystal structure. Within the low pressure phase, Bi2Se3 exhibits an unusual field dependence of the transverse magnetoresistance that is positive at low fields and becomes negative at higher fields. Our results demonstrate that pressures below 8 GPa provide a non-chemical means to controllably reduce the bulk conductivity of Bi2Se3
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