Evidence for Kosterlitz-Thouless and three-dimensionalXYcritical behavior inBi2Sr2CaCu

Abstract

We present reversible magnetization data of a high quality Bi2Sr2CaCu2O 8+δ single crystal and explore the occurrence of 3D-xy critical behavior close to the bulk transition temperature Tc and of Kosterlitz-Thouless (KT) behavior. Below and above the presumed Kosterlitz-Thouless transition temperature TKT we observe the characteristic 2D-xy behavior: a downward shift of the crossing point phenomenon towards TKT as the field is decreased and sufficiently below TKT the characteristic 2D-xy relationship between the magnetization an the in-plane magnetic penetration depth λ ab . In contrast, the measured temperature dependence of the superfluid density does not exhibit the characteristic KT-behavior around the presumed TKT. The absence of this feature is traced back to the 2D-to 3D-xy crossover setting in around and above TKT. Invoking the Maxwell relation, the anomalous field dependence of the specific heat peak is also traced back to the intermediate 2D-xy behavior. However, close to Tc we observe consistency with 3D-xy critical behavior, in agreement with measurements of λ ab .

Evolution of superconducting correlations within magnetic-field-decoupled La2−xBaxCuOStegen1, Han2, Wu3 et al. 2013Phys. Rev. B338320View full textAdd to dashboardCite

“…T c0 is slightly larger than T 2D c , suggesting that, upon cooling in zero field, 3D order develops just before the individual layers would become superconducting in the absence of Josephson coupling, as others have observed in Bi 2 Sr 2 CaCu 2 O 8+δ . [79][80][81] The LVL state that we observe here only at finite H ⊥ is equivalent to the state previously detected in LBCO x = 1 8 below 40 K in zero field. 40 We compare the phase diagrams of these two compositions in Fig.…”

Diamagnetism, Nernst signal, and finite-size effects in superconductors above the transition temperatureTc

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Influence of thermal phase fluctuations on the spectral function for a two-dimensionald-wave superconductor

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