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arXiv · 0811.1253

Systematic characterization of upper critical fields for MgB$_2$ thin films using the two-band superconducting theory

S. Noguchi·A. Kuribayashi·T. Ishida·T. Oba·H. Iriuda·M. Yoshizawa·Y. Harada·S. Miki·H. Shimakage·Z. Wang·K. Satoh·T. Yotsuya
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Abstract

We present experimental results of the upper critical fields $H_{\rm c2}$ of various MgB$_2$ thin films prepared by the molecular beam epitaxy, multiple-targets sputtering, and co-evaporation deposition apparatus. Experimental data of the $H_{\rm c2}(T)$ are successfully analyzed by applying the Gurevich theory of dirty two-band superconductivity in the case of $D_π/D_σ>1$, where $D_π$ and $D_σ$ are the intraband electron diffusivities for $π$ and $σ$ bands, respectively. We find that the parameters obtained from the analysis are strongly correlated to the superconducting transition temperature $T_{\rm c}$ of the films. We also discuss the anormalous narrowing of the transition width at intermediate temperatures confirmed by the magnetoresistance measurements.

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S. Noguchi, A. Kuribayashi, T. Ishida, T. Oba, H. Iriuda, M. Yoshizawa, Y. Harada, S. Miki, H. Shimakage, Z. Wang, K. Satoh, T. Yotsuya. 2008-11-08. Systematic characterization of upper critical fields for MgB$_2$ thin films using the two-band superconducting theory. https://doi.org/10.1088/0953-2048%2F22%2F5%2F055004

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