Structural phase transition, precursory electronic anomaly, and strong-coupling superconductivity in quasi-skutterudite (Sr1-xCax)(3)Ir4Sn13 and Ca3Rh4Sn13
Structural phase transition, precursory electronic anomaly, and strong-coupling superconductivity in quasi-skutterudite (Sr1-xCax)(3)Ir4Sn13 and Ca3Rh4Sn13
复制标题
准方钴矿 (Sr1-xCax)(3)Ir4Sn13 和 Ca3Rh4Sn13 中的结构相变、前兆电子异常和强耦合超导
DOI：
10.1088/1674-1056/27/7/077401
复制
发表时间：
2018
影响因子：
1.7
通讯作者：
Zheng Guo-Qing
中科院分区：
文献类型：
--
作者：
Luo Jun;Yang Jie;Maeda S.;Li Zheng;Zheng Guo-Qing
近年来，超导性与结构相变之间的相互作用引起了人们极大的兴趣。例如，在Fe-磷属元素化物高温超导体中，与结构相变相关的量子涨落已经被提出导致许多新的物理性质，甚至超导性本身。本文报道了通过119 Sn核磁共振（NMR）测量发现的准方钴矿超导体（Sr 1− xCax）3 Ir 4Sn 13（x= 0，0.5，1）和Ca 3Rh 4Sn 13具有与铁磷属元素化合物类似的特殊性质。在（Sr 1-xCax）3 Ir 4Sn 13中，NMR线宽在高于结构相变温度Ts的温度T* 以下增加。自旋-晶格弛豫速率（1/T1）除以温度（T）、1/T1 T和Knight位移K随T的减小而增大，但在T* 以下开始减小，在Ts处变化更为明显.与此相反，没有观察到的异常Ca 3Rh 4Sn 13不经历结构相变。在结构相变之上的超晶格现象类似于Fe-磷属元素化物中的超晶格现象。在超导态Ca 3 Ir 4Sn 13中，1/T1随exp（-Δ/k B T）衰减，带隙Δ= 2.21k B Tc，但没有Hebel-Slichter相干峰，表明具有强耦合超导性.我们的研究结果提供了新的见解超导性和电子结构的变化与结构相变之间的关系。
The interplay between superconductivity and structural phase transition has attracted enormous interest in recent years. For example, in Fe-pnictide high temperature superconductors, quantum fluctuations in association with structural phase transition have been proposed to lead to many novel physical properties and even the superconductivity itself. Here we report a finding that the quasi-skutterudite superconductors (Sr 1− x Ca x) 3 Ir 4 Sn 13 (x= 0, 0.5, 1) and Ca 3 Rh 4 Sn 13 show some unusual properties similar to the Fe-pnictides, through 119 Sn nuclear magnetic resonance (NMR) measurements. In (Sr 1− x Ca x) 3 Ir 4 Sn 13, the NMR linewidth increases below a temperature T* that is higher than the structural phase transition temperature T s. The spin-lattice relaxation rate (1/T 1) divided by temperature (T), 1/T 1 T and the Knight shift K increase with decreasing T down to T*, but start to decrease below T*, and followed by more distinct changes at T s. In contrast, none of the anomalies is observed in Ca 3 Rh 4 Sn 13 that does not undergo a structural phase transition. The precursory phenomenon above the structural phase transition resembles that occurring in Fe-pnictides. In the superconducting state of Ca 3 Ir 4 Sn 13, 1/T 1 decays as exp (− Δ/k B T) with a large gap Δ= 2.21k B T c, yet without a Hebel–Slichter coherence peak, which indicates strong-coupling superconductivity. Our results provide new insight into the relationship between superconductivity and the electronic-structure change associated with structural phase transition.