728 research outputs found

    Theory of the magnetoeletric effect in a lightly doped high-Tc cuprate

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    In a recent study Viskadourakis et al. discovered that extremely underdoped La_2CuO_(4+x) is a relaxor ferroelectric and a magnetoelectric material at low temperatures. It is further observed that the magnetoelectric response is anisotropic for different directions of electric polarization and applied magnetic field. By constructing an appropriate Landau theory, we show that a bi-quadratic magnetoelectric coupling can explain the experimentally observed polarization dependence on magnetic field. This coupling leads to several novel low-temperature effects including a feedback enhancement of the magnetization below the ferroelectric transition, and a predicted magnetocapacitive effect.Comment: 5 pages, 4 figure

    PDTL: Parallel and distributed triangle listing for massive graphs

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    Mesothelioma: t(14;22)(q32;q12) in mesothelioma

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    Short communication on t(14;22)(q32;q12) in mesothelioma with data on clinics

    Penetration Depth Measurements in MgB_2: Evidence for Unconventional Superconductivity

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    We have measured the magnetic penetration depth of the recently discovered binary superconductor MgB_2 using muon spin rotation and low field acac-susceptibility. From the damping of the muon precession signal we find the penetration depth at zero temperature is about 85nm. The low temperature penetration depth shows a quadratic temperature dependence, indicating the presence of nodes in the superconducting energy gap.Comment: 4 pages 3 figure

    Large Positive Magnetoresistance of the Lightly Doped La_{2}CuO_{4} Mott Insulator

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    The in-plane and out-of-plane magnetoresistance (MR) of single crystals of La_2CuO_4, lightly doped (x=0.03) with either Sr (La_{2-x}Sr_xCuO_4) or Li (La_2Cu_{1-x}Li_xO_4), have been measured in the fields applied parallel and perpendicular to the CuO_2 planes. Both La_{1.97}Sr_{0.03}CuO_4 and La_2Cu_{0.97}Li_{0.03}O_4 exhibit the emergence of a positive MR at temperatures (T) well below the spin glass (SG) transition temperature T_{sg}, where charge dynamics is also glassy. This positive MR grows as T->0 and shows hysteresis and memory. In this regime, the in-plane resistance R_{ab}(T,B) is described by a scaling function, suggesting that short-range Coulomb repulsion between two holes in the same disorder-localized state plays a key role at low T. The results highlight similarities between this magnetic material and a broad class of well-studied, nonmagnetic disordered insulators.Comment: 5+ pages, 3 figures; published versio
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