1,847 research outputs found

    Correlation between TcT_c and anisotropic scattering in Tl2_2Ba2_2CuO6+δ_{6+\delta}

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    Angle-dependent magnetoresistance measurements are used to determine the isotropic and anisotropic components of the transport scattering rate in overdoped Tl2_2Ba2_2CuO6+δ_{6+\delta} for a range of TcT_c values between 15K and 35K. The size of the anisotropic scattering term is found to scale linearly with TcT_c, establishing a link between the superconducting and normal state physics. Comparison with results from angle resolved photoemission spectroscopy indicates that the transport and quasiparticle lifetimes are distinct.Comment: 5 pages, 3 figures, accepted for publication in Physical Review Letter

    Avoiding Misuse of Donor Advised Funds

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    This Article presents a proposal for further modifying donor advised funds to retain most of their hallmark flexibility and ease of use while drawing them into line with other charitable giving vehicles that put contributed funds to use for active charitable purposes. This Article argues that using individual retirement accounts as an underlying legal model for donor advised funds will address Congress\u27s concerns regarding the appropriateness of the income tax deductions for contributions to donor advised funds while allowing donor advised funds to retain much of their hallmark flexibility and ease of operation

    Destruction of chain-superconductivity in YBa_2Cu_4O_8 in a weak magnetic field

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    We report measurements of the temperature dependent components of the magnetic penetration depth {\lambda}(T) in single crystal samples of YBa_2Cu_4O_8 using a radio frequency tunnel diode oscillator technique. We observe a downturn in {\lambda}(T) at low temperatures for currents flowing along the b and c axes but not along the a axis. The downturn in {\lambda}_b is suppressed by a small dc field of ~0.25 T. This and the zero field anisotropy of {\lambda}(T) likely result from proximity induced superconducting on the CuO chains, however we also discuss the possibility that a significant part of the anisotropy might originate from the CuO2 planes.Comment: 5 page

    Linear magnetoresistance in a quasi-free two dimensional electron gas in an ultra-high mobility GaAs quantum well

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    We report a magnetotransport study of an ultra-high mobility (μˉ25×106\bar{\mu}\approx 25\times 10^6\,cm2^2\,V1^{-1}\,s1^{-1}) nn-type GaAs quantum well up to 33 T. A strong linear magnetoresistance (LMR) of the order of 105^5 % is observed in a wide temperature range between 0.3 K and 60 K. The simplicity of our material system with a single sub-band occupation and free electron dispersion rules out most complicated mechanisms that could give rise to the observed LMR. At low temperature, quantum oscillations are superimposed onto the LMR. Both, the featureless LMR at high TT and the quantum oscillations at low TT follow the empirical resistance rule which states that the longitudinal conductance is directly related to the derivative of the transversal (Hall) conductance multiplied by the magnetic field and a constant factor α\alpha that remains unchanged over the entire temperature range. Only at low temperatures, small deviations from this resistance rule are observed beyond ν=1\nu=1 that likely originate from a different transport mechanism for the composite fermions