We have magnetically imaged interlayer Josephson vortices emerging from an ac face of single crystals of the single layer cuprate high-T c superconductor (Hg,Cu)Ba 2 CuO 4+δ . These images provide a direct measurement of the c-axis penetration depth, λ c ∼ 10 µm. This length is a factor of 10 longer than predicted by the interlayer tunneling model for the mechanism of superconductivity in layered compounds, indicating that the condensation energy available through this mechanism is 100 times smaller than is required for superconductivity.

Generalized Flory-Huggins theory-based equation of state for ring and chain fluids J. Chem. Phys. 136, 124904 (2012) The plastic and liquid phases of CCl3Br studied by molecular dynamics simulations J. Chem. Phys. 136, 094515 (2012) Rheological, optical, and thermal characterization of temperature-induced transitions in liquid crystal ferrosuspensions J. Appl. Phys. 111, 07B308 (2012) Comment on "Design of acoustic devices with isotropic material via conformal transformation" [Appl. Phys. Lett. 97, 044101 (2010)] Appl. Phys. Lett. 100, 066101 (2012) The role of the isothermal bulk modulus in the molecular dynamics of super-cooled liquids

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We report on the London penetration depth ab (0), measurements, and second peak H determination in Bi 2 Sr 2 Ca 1Ϫx Y x Cu 2 O 8ϩ␦ ͑Bi-2212͒ crystals with different doping levels. By combining cationic substitutions and oxygen pressure annealings, crystals with a doping state going from the underdoped to overdoped regime have been obtained. The corresponding ab (0) values, deduced from reversible magnetization measurements have allowed us to evidence a ''boomerang'' shape for the T c ͓1/ ab 2 (0)͔ curve in the 0.8рT c /T c max р1 region. Moreover, other T c ͓1/ ab 2 (0)͔ values for superconducting crystals of Hg-and Tl-based cuprates are found to fit well with this boomerang path, demonstrating its universal nature. The overdoped side of the boomerang for the Bi-2212 crystals clearly shows that 1/ ab 2 (0) decreases as the doping level is increased. Since by the same time the characteristic field of the fishtail H monotonously increases, we have thus established that H increases with 1/ ab 2 (0) decreasing. Consequently, the linear relation H ϭ⌽ 0 / ab 2 (0) predicted by the electromagnetic model cannot account alone for the present experimental results in the overdoped regime.

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