Matsushita Y, Bluhm H, Geballe T H, Fisher I R
Department of Materials Science and Engineering and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305-4045, USA.
Phys Rev Lett. 2005 Apr 22;94(15):157002. doi: 10.1103/PhysRevLett.94.157002. Epub 2005 Apr 21.
We report results of low-temperature thermodynamic and transport measurements of Pb1-xTlxTe 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) approximately 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.
我们报告了Pb1-xTlxTe单晶的低温热力学和输运测量结果，其中铊（Tl）浓度高达约x = 1.5%的溶解度极限。对于所有掺杂样品，我们观察到低温电阻率上升，其幅度随Tl浓度而变化。这种上升的温度和磁场依赖性与涉及价态简并且相差两个电子的Tl的电荷近藤效应一致，特征近藤温度T(K)约为6 K。这种效应的观测支持了该材料中超导性的电子配对机制，并可能解释其异常高的Tc值。
