Observation of a ubiquitous three-dimensional superconducting gap function in optimally doped Ba0.6K0.4Fe2As2
Observation of a ubiquitous three-dimensional superconducting gap function in optimally doped Ba0.6K0.4Fe2As2
复制标题
观察最佳掺杂 Ba0.6K0.4Fe2As2 中普遍存在的三维超导带隙函数
DOI：
10.1038/nphys1879
复制
发表时间：
2011-03-01
期刊：
影响因子：
19.6
通讯作者：
Ding, H.
中科院分区：
文献类型：
--
作者：
Xu, Y-M.;Huang, Y-B.;Ding, H.
铁-磷属元素化物超导体具有由FeAs平面堆叠形成的层状结构，超导性起源于FeAs平面。考虑到这些高温超导体的多带和准三维（1）（3D）电子结构，准3D超导（SC）能隙的知识对于理解超导机制是必不可少的。利用角分辨光电子能谱的k（z）能力，我们完全确定了Ba_（0.6）K_（0.4）Fe_2As_2样品所有5个Fermi面（FS）上的SC能隙。我们发现了一个显着的kz分散的SC间隙，这只能来自层间配对。值得注意的是，SC能隙可以通过具有表征层内Delta（1）和层间Delta（2）配对的强度的两个能量尺度的单个3D能隙函数来描述。由差距函数确定的各向异性比Delta（1）/Delta（2）接近于母体化合物（2）中磁交换耦合J（c）/J（ab）的c轴各向异性比。普遍存在的间隙函数的所有3D FS显示，配对是短程的，并强烈约束可能的pnictides的配对力。一个合适的候选者可能来自短程反铁磁波动。
The iron-pnictide superconductors have a layered structure formed by stacks of FeAs planes from which the superconductivity originates. Given the multiband and quasi three-dimensional(1) (3D) electronic structure of these high-temperature superconductors, knowledge of the quasi-3D superconducting (SC) gap is essential for understanding the superconducting mechanism. By using the k(z) capability of angle-resolved photoemission, we completely determined the SC gap on all five Fermi surfaces (FSs) in three dimensions on Ba0.6K0.4Fe2As2 samples. We found a marked kz dispersion of the SC gap, which can derive only from interlayer pairing. Remarkably, the SC energy gaps can be described by a single 3D gap function with two energy scales characterizing the strengths of intralayer Delta(1) and interlayer Delta(2) pairing. The anisotropy ratio Delta(1)/Delta(2), determined from the gap function, is close to the c-axis anisotropy ratio of the magnetic exchange coupling J(c)/J(ab) in the parent compound(2). The ubiquitous gap function for all the 3D FSs reveals that pairing is short-ranged and strongly constrains the possible pairing force in the pnictides. A suitable candidate could arise from short-range antiferromagnetic fluctuations.