摘要
The iron-chalcogenide high temperature superconductor Fe(Se,Te)(FST) has been reported to exhibit complex magnetic ordering and nontrivial band topology which may lead to novel superconducting phenomena. However, the recent studies have so far been largely concentrated on its band and spin structures while its mesoscopic electronic and magnetic response, crucial for future device applications, has not been explored experimentally. Here, we used scanning superconducting quantum interference device microscopy for its sensitivity to both local diamagnetic susceptibility and current distribution in order to image the superfluid density and supercurrent in FST. We found that in FST with 10% interstitial Fe,whose magnetic structure was heavily disrupted, bulk superconductivity was significantly suppressed whereas edge still preserved strong superconducting diamagnetism. The edge dominantly carried supercurrent despite of a very long magnetic penetration depth. The temperature dependences of the superfluid density and supercurrent distribution were distinctively different between the edge and the bulk.Our Heisenberg modeling showed that magnetic dopants stabilize anti-ferromagnetic spin correlation along the edge, which may contribute towards its robust superconductivity. Our observations hold implication for FST as potential platforms for topological quantum computation and superconducting spintronics.
铁硫族超导体Fe(Se,Te)由于具有较强自旋轨道耦合而被认为可能存在拓扑超导特性.对于具有多余磁性杂质的Fe_(1+y)(Se,Te),之前的实验发现过量Fe的自旋磁矩导致配对电子自旋关联的破坏,从而大幅度压制了块材的超流密度.通过扫描超导量子干涉仪(sSQUID)精密探测这样的Fe_(1+y)(Se,Te)的局部抗磁特性,本文发现铁掺杂对超导的压制主要出现在块材内部,而边界的超导性则无明显减弱.测量结果展示了边界超导与铁不过量Fe(Se,Te)几乎拥有相等的超导转变温度,以及超流密度和超导电流在边界的集中分布.通过排除外界因素的影响,这样的强健边界超导是Fe(Se,Te)的本征性质,并可能与其拓扑超导性相关.该文还使用海森堡自旋模型分析了反铁磁自旋关联在边界与体的差别,并为反铁磁关联作为铁基超导微观机制提供了新的研究线索.
作者
Da Jiang
Yinping Pan
Shiyuan Wang
Yishi Lin
Connor M.Holland
John R.Kirtley
Xianhui Chen
Jun Zhao
Lei Chen
Shaoyu Yin
Yihua Wang
姜达;潘银萍;王世源;林一石;Connor M.Holland;John R.Kirtley;陈仙辉;赵俊;陈垒;尹少禹;王熠华(Shanghai Institute of Microsystem and Information Technology,Shanghai 200050,China;State Key Laboratory of Surface Physics and Department of Physics,Fudan University,Shanghai 200433,China;Department of Physics,Stanford University,Stanford,CA 94305,USA;Department of Physics,University of Science and Technology of China,Hefei 230026,China;Institute for Theoretical Physics and Cosmology,Zhejiang University of Technology,Hangzhou 310023,China;Shanghai Research Center for Quantum Sciences,Shanghai 201315,China)
基金
Yihua Wang would like to acknowledge partial support by the Ministry of Science and Technology of China(2016YFA0301002 and 2017YFA0303000)
the National Natural Science Foundation of China(11827805)
Shanghai Municipal Science and Technology Major Project Da Jiang would like to acknowledge partial support by the‘‘Strategic Priority Research Program(B)”of the Chinese Academy of Sciences(XDB04040300)
the National Natural Science Foundation of China(11274333)
Hundred Talents Program of the Chinese Academy of Sciences.Shaoyu Yin would like to acknowledge support by the National Natural Science Foundation of China(11704072)
Work at Stanford was supported by an NSF IMR-MIP(DMR-0957616)
part of the National Nanotechnology Coordinated Infrastructure under award ECCS-1542152.
