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Two types of Hc2(T) dependences in Bi_2Sr_2Ca_(1-x)Y_xCu_2O_(8+delta) with different Yttrium content

I. L. Landau·H. Keller
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Abstract

We reanalyze the magnetization data collected on Bi_2Sr_2Ca_(1-x)Y_xCu_2O_(8+y) samples (Kim at al, Phys. Rev. B 72, 64525 (2005)) and argue that the method, which was used for the analysis of equilibrium magnetization data, is not adequate to the experimental situation. As a result, the temperature dependencies of the upper critical field Hc2(T) and the magnetic field penetration depth lambda (T), obtained in this work, are misinterpreted. Using a different approach to analysis, we demonstrate that the normalizedHc2(T) curves are rather different from those presented in the original publication and do not follow predictions of the Werthamer-Helfand-Hohenberg theory. Another important observation is that the Hc2(T) dependencies for two samples with different levels of doping are qualitatively different.

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I. L. Landau, H. Keller. 2006-12-01. Two types of Hc2(T) dependences in Bi_2Sr_2Ca_(1-x)Y_xCu_2O_(8+delta) with different Yttrium content. https://doi.org/10.1016/j.physc.2007.03.374

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