Temperature dependence of the microwave surface impedance measured on different kinds of MgB$_2$ samples

A. A. Zhukov; L. F. Cohen; A. Purnell; Y. Bugoslavsky; A. Berenov; J. L. MacManus-Driscoll; H. Y Zhai; Hans M. Christen; Mariappan P. Paranthaman; Douglas H. Lowndes; M. A. Jo; M. C. Blamire; Ling Hao; J. Gallop

arXiv · cond-mat/0107240

Temperature dependence of the microwave surface impedance measured on different kinds of MgB$_2$ samples

A. A. Zhukov·L. F. Cohen·A. Purnell·Y. Bugoslavsky·A. Berenov·J. L. MacManus-Driscoll·H. Y Zhai·Hans M. Christen·Mariappan P. Paranthaman·Douglas H. Lowndes·M. A. Jo·M. C. Blamire·Ling Hao·J. Gallop

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Abstract

In this paper we present the results of measurements of the microwave surface impedance of a powder sample and two films of MgB$_2$. One film has $T_c=30$ K and is not textured, the other is partially c-axis orientated with $T_c=38$ K. These samples show different types of temperature dependence of the field penetration depth: linear for the powder sample, exponential with $Δ/kT_c<1.76$ (film with $T_c=30$ K) and strong coupling behaviour with $Δ/kT_c\sim 2.25$ (film with $T_c=38$ K). The results are well described in terms of an anisotropic gap model or presence of a slightly deficient MgB$_2$ phase. The data set for all samples - taken as a whole cannot be fitted into a two gap scenario.

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A. A. Zhukov, L. F. Cohen, A. Purnell, Y. Bugoslavsky, A. Berenov, J. L. MacManus-Driscoll, H. Y Zhai, Hans M. Christen, Mariappan P. Paranthaman, Douglas H. Lowndes, M. A. Jo, M. C. Blamire, Ling Hao, J. Gallop. 2001-07-15. Temperature dependence of the microwave surface impedance measured on different kinds of MgB$_2$ samples. https://arxiv.org/abs/cond-mat/0107240

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