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Evidence for charge Kondo effect in superconducting Tl-doped PbTe

Y. Matsushita·H. Bluhm·T. H. Geballe·I. R. Fisher
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Abstract

We report results of low-temperature thermodynamic and transport measurements of Pb_{1-x}Tl_{x}Te single crystals for Tl concentrations up to the solubility limit of approximately x = 1.5%. For all doped samples, we observe a low-temperature resistivity upturn that scales in magnitude with the Tl concentration. The temperature and field dependence of this upturn are consistent with a charge Kondo effect involving degenerate Tl valence states differing by two electrons, with a characteristic Kondo temperature T_K ~ 6 K. The observation of such an effect supports an electronic pairing mechanism for superconductivity in this material and may account for the anomalously high T_c values.

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Y. Matsushita, H. Bluhm, T. H. Geballe, I. R. Fisher. 2005-02-08. Evidence for charge Kondo effect in superconducting Tl-doped PbTe. https://doi.org/10.1103/physrevlett.94.157002

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