21 research outputs found

    3D-XY critical fluctuations of the thermal expansivity in detwinned YBa2Cu3O7-d single crystals near optimal doping

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    The strong coupling of superconductivity to the orthorhombic distortion in YBa2Cu3O7-d makes possible an analysis of the superconducting fluctuations without the necessity of subtracting any background. The present high-resolution capacitance dilatometry data unambiguously demonstrate the existence of critical, instead of Gaussian, fluctuations over a wide temperature region (+/- 10 K) around Tc. The values of the amplitude ratio A+/A-=0.9-1.1 and the leading scaling exponent |alpha|<0.018, determined via a least-squares fit of the data, are consistent with the 3D-XY universality class. Small deviations from pure 3D-XY behavior are discussed.Comment: 11 pages including three figure

    The Effect of Chemical Doping and Hydrostatic Pressure on Tc of Y1-yCayBa2Cu3Ox Single Crystals

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    We performed susceptibility measurements on Y1-yCayBa2Cu3Ox single crystals under high He pressure. For each Ca content various samples with different oxygen contents have been prepared to probe the influence of Ca on Tc(x), dTc/dp(x) and Tc,max. Starting from the parabolic Tc(nh) behavior we calculated nh values from Tc and Tc,max for each sample. It is shown that in the overdoped region dTc/dp can be described by a pressure induced charge transfer with dnh/dp = 3.7E-3 [1/GPa] and a dTc,max/dp value of 0.8 K/GPa, irrespective of the Ca content. In the underdoped region additional pressure effects lead to a peak in dTc/dp at approximately 0.11 holes/CuO2 plane. However, with increasing Ca content this peak is strongly depressed. This is explained in terms of an increasing disorder in the CuO chain system due to doping. Deviations in dTc/dp at very low nh values can be assigned to the ortho II ordering in the CuO chain system.Comment: 13 pages with 6 figures, accepted for publication in Physica

    Chemnitzer Linux-Tage 2010: Tagungsband – 13. und 14. MĂ€rz 2010

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    Die Chemnitzer Linux-Tage fanden am 13. und 14. MĂ€rz 2010 auf dem Campus der Technischen UniversitĂ€t Chemnitz statt. Neben den PrĂ€sentationen im Foyer zogen vor allem die VortrĂ€ge ĂŒber 2500 Besucher zur 12. Auflage der Veranstaltung. Der Band vereint den Inhalt von 15 HauptvortrĂ€gen und die Abstrakts von 76 weiteren BeitrĂ€gen und stellt damit einen Überblick ĂŒber das weit gefĂ€cherte Programm der Veranstaltung dar.The Chemnitz Linux Days took place at the campus of the Chemnitz University of Technology. Besides the presentations at the foyer the lectures were first of all attractive for more than 2.500 visitors. This volume contains the content of 15 main lectures and abstracts of 76 further talks and hence gives a survey of the broadly based program of this event
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