Robustness of superconductivity to structural disorder in Sr 0.3 ( NH 2 ) y ( NH 3 ) 1 - y Fe 2 Se 2
Robustness of superconductivity to structural disorder in Sr 0.3 ( NH 2 ) y ( NH 3 ) 1 - y Fe 2 Se 2
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Sr 0.3 ( NH 2 ) y ( NH 3 ) 1 - y Fe 2 Se 2 中超导性对结构无序的鲁棒性
DOI：
10.1103/physrevb.92.134517
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发表时间：
2015
影响因子：
3.7
通讯作者：
Foronda F
中科院分区：
文献类型：
--
作者：
Foronda F
最近发现的高超导体 Sr/氨插层 FeSe 的超导特性，已使用低至 4.2 K 的脉冲磁场和低至 1.5 K 的 μ 子自旋光谱进行了测量。这种化合物表现出因 FeSe 层沿轴随机堆叠而产生的内在无序性，而同一族的其他插层体中不存在这种无序性。出现这种情况是因为插入的 Sr 和氨部分的配位要求意味着层间堆叠（沿）涉及局部破坏四方对称性的任一或一个的平移。这种堆叠排列的结果是，该化合物中的 Fe 离子形成体心四方晶格，这与所有其他铁基超导体中描述的 Fe 离子的原始排列形成鲜明对比。在脉冲磁场中，发现上临界场随着冷却而增加，并具有向上的曲率，这在多带性质的 II 型超导体中常见。将数据拟合到双带模型并外推至绝对零给出最大上临界场。在横向场 μ 子测量中也观察到具有抗磁位移的清晰超导转变。这些结果表明，这些插层 FeSe 系统中强大的超导性并不依赖于沿轴的完美结构相干性。
The superconducting properties of a recently discovered high-superconductor, Sr/ammonia-intercalated FeSe, have been measured using pulsed magnetic fields down to 4.2 K and muon spin spectroscopy down to 1.5 K. This compound exhibits intrinsic disorder resulting from random stacking of the FeSe layers along theaxis that is not present in other intercalates of the same family. This arises because the coordination requirements of the intercalated Sr and ammonia moieties imply that the interlayer stacking (along) involves a translation of eitherorthat locally breaks tetragonal symmetry. The result of this stacking arrangement is that the Fe ions in this compound describe a body-centered-tetragonal lattice in contrast to the primitive arrangement of Fe ions described in all other Fe-based superconductors. In pulsed magnetic fields, the upper critical fieldwas found to increase on cooling with an upward curvature that is commonly seen in type-II superconductors of a multiband nature. Fitting the data to a two-band model and extrapolation to absolute zero gave a maximum upper critical fieldof. A clear superconducting transition with a diamagnetic shift was also observed in transverse-field muon measurements at. These results demonstrate that robust superconductivity in these intercalated FeSe systems does not rely on perfect structural coherence along theaxis.