3,285 research outputs found

    Are Investors the Bad Guys? Tenure and Neighborhood Stability in Chelsea, Massachusetts

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    In this article, we examine the role of investors and occupant-owners in an urban context during the recent housing crisis. We focus on Chelsea, Massachusetts, because it is a dense city, dominated by multifamily housing structures with high rates of foreclosure for which we have particularly good data. We distinguish between occupant-owners and investors using local data, and we find that many investors are misclassified as occupant-owners in the Home Mortgage Disclosure Act data. Then, employing a competing risks framework to study ownerships during the period 1998 through mid-2010, we find that local investors, who tend to invest more in relation to purchase prices and sell more quickly, experienced approximately 1.8 times the mortgage foreclosure risk of occupant-owners, conditional on financing. Nonlocal investors have no statistically significant difference in foreclosure risk from occupant-owners. Nonetheless, those owners with subprime purchase mortgages (most of whom are occupant-owners) faced the highest foreclosure risk when house prices fell

    SO(5) Invariance and Effective Field Theory for High-Tc Superconductors

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    We set up the effective field theories which describe the SO(5)-invariant picture of the high-Tc cuprates in various regimes. We use these to get quantitative conclusions concerning the size of SO(5)-breaking effects. We consider two applications in detail: (i) the thermodynamic free energy, which describe the phase diagram and critical behaviour, and (ii) the Lagrangian governing the interactions of the pseudo-Goldstone bosons with each other and with the electron quasiparticles deep within the ordered phases. We use these effective theories to obtain predictions for the critical behaviour near the possible bicritical point and the pseudo-Goldstone boson dispersion relations, as well as some preliminary results concerning their contribution to response functions. We systematically identify which predictions are independent of the microscopic details of the underlying electron dynamics, and which depend on more model-dependent assumptions.Comment: 40 pages, plain TeX, companion article for the letter cond-mat/961107

    Anomalous ferromagnetic spin fluctuations in an antiferromagnetic insulator Pr_{1-x}Ca_{x}MnO_{3}

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    The high temperature paramagnetic state in an antiferromagnetic (AFM) insulator Pr_{1-x}Ca_{x}MnO_{3} is characterized by the ferromagnetic (FM) spin fluctuations with an anomalously small energy scale. The FM fluctuations show a precipitous decrease of the intensity at the charge ordering temperature T_{CO}, but persist below T_{CO}, and vanish at the AFM transition temperature T_{N}. These results demonstrate the importance of the spin ordering for the complete switching of the FM fluctuation in doped manganites.Comment: REVTeX, 5 pages, 4 figures, submitted to Phys. Rev.

    Anisotropic three-dimentional magnetic fluctuations in heavy fermion CeRhIn5

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    CeRhIn5 is a heavy fermion antiferromagnet that orders at 3.8 K. The observation of pressure-induced superconductivity in CeRhIn5 at a very high Tc of 2.1 K for heavy fermion materials has led to speculations regarding to its magnetic fluctuation spectrum. Using magnetic neutron scattering, we report anisotropic three-dimensional antiferromagnetic fluctuations with an energy scale of less than 1.7 meV for temperatures as high as 3Tc. In addition, the effect of the magnetic fluctuations on electrical resistivity is well described by the Born approximation.Comment: 4 pages, 4 figure
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