Crystal structure, physical properties and superconductivity in AxFe2Se2 single crystals
Crystal structure, physical properties and superconductivity in AxFe2Se2 single crystals
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DOI：
10.1088/1367-2630/13/5/053011
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发表时间：
2011-05-09
影响因子：
3.3
通讯作者：
Chen, X. H.
中科院分区：
文献类型：
--
作者：
Luo, X. G.;Wang, X. F.;Chen, X. H.
本文研究了不同A（x）Fe（2）Se（2）单晶（A = K，Rb和Cs）的结构、输运性质和超导电性之间的关系。在X射线单晶衍射图中观察到两组（00l）反射，它们是由插入的碱原子的本征不均匀分布引起的。超导电性的发生与c轴晶格常数密切相关，A含量对超导电性至关重要。在电阻率中观察到的驼峰似乎与超导性无关。在A（x）Fe（2）Se（2）中，虽然FeSe层的Tc变化不大，但FeSe层内存在许多缺陷。在这个意义上，超导性对FeSe层内的空位是稳健的。正常状态下非常高的电阻率应归因于导电FeSe层中的这种缺陷。A（x）Fe（2）Se（2）（A = K，Rb和Cs）单晶在正常状态下表现出相同的磁化率行为，在电阻率峰温处未观察到磁化率异常。RbxFe_2Se_2和KxFe_2Se_2单晶比热的明显跳跃表明这些晶体具有良好的体超导性。
We studied the correlation among structure, transport properties and superconductivity in different A(x)Fe(2)Se(2) single crystals (A = K, Rb and Cs). Two sets of (00l) reflections are observed in the x-ray single-crystal diffraction patterns, and they arise from the intrinsic inhomogeneous distribution of the intercalated alkali atoms. The occurrence of superconductivity is closely related to the c-axis lattice constant, and the A content is crucial to superconductivity. The hump observed in resistivity seems to be irrelevant to the superconductivity. There exist many deficiencies within the FeSe layers in A(x)Fe(2)Se(2), although their T-c does not change so much. In this sense, superconductivity is robust to the vacancies within the FeSe layers. Very high resistivity in the normal state should be ascribed to such defects in the conducting FeSe layers. A(x)Fe(2)Se(2) (A = K, Rb and Cs) single crystals show the same susceptibility behavior in the normal state, and no anomaly is observed in susceptibility at the hump temperature in resistivity. The clear jump in specific heat for RbxFe2Se2 and KxFe2Se2 single crystals indicates the good bulk superconductivity of these crystals.