Superconductivity and pseudogap features of an isolated FeAs layer in KCa_(2)Fe_(4)As_(4)F_(2) unraveled by STM/STS  

作　　者：Shuai Shao Fan Zhang Zongyuan Zhang Teng Wang Yanwei Wu Yubing Tu Jie Hou Xingyuan Hou Ning Hao Gang Mu Lei Shan 

机构地区：[1]Information Materials and Intelligent Sensing Laboratory of Anhui Province,Institutes of Physical Science and Information Technology,Anhui University,Hefei 230601,China [2]Key Laboratory of Structure and Functional Regulation of Hybrid Materials(Anhui University),Ministry of Education,Hefei 230601,China [3]Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China [4]State Key Laboratory of Functional Materials for Informatics,Shanghai Institute of Microsystem and Information Technology,Chinese Academy of Sciences,Shanghai 200050,China [5]Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions,High Magnetic Field Laboratory Hefei Institutes of Physical Science(HFIPS),Chinese Academy of Sciences,University of Science and Technology of China,Hefei 230031,China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2023年第8期131-138,共8页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the National Key Research and Development Program of China(Grant Nos.2018YFA0305602,2022YFA1403203,and 2017YFA0303201);the National Natural Science Foundation of China(Grant Nos.12074002,92265104,12022413,11674331,and 12104004);the“Strategic Priority Research Program(B)”of the Chinese Academy of Sciences(Grant No.XDB33030100);the Major Basic Program of Natural Science Foundation of Shandong Province(Grant No.ZR2021ZD01);supported by the High Magnetic Field Laboratory of Anhui Province,China。

摘　　要：To reveal the intrinsic properties of the basic superconducting units,i.e.,the single layered FeSe/FeAs in iron-based superconductors or CuO_(2) planes in cuprate superconductors,is a necessary prerequisite for understanding the mechanism of high-Tc superconductivity.Up to now,an isolated FeAs layer has rarely been studied due to the difficulty in materials synthesis.Here,we report a scanning tunneling microscopy/spectroscopy(STM/STS)study on the iron-based superconductor KCa_(2)Fe_(4)As_(4)F_(2).In situ cleavage produced a single FeAs layer covered by a reconstructed K surface,which is isolated from the bulk by the underlying CaF layer and shows multi-band superconductivity with a much lower T_(c) than its bulk counterpart.In the exposed As-terminated regions with coverage of scattered K atoms,a pseudogap was observed,leading to an inhomogeneous superconductivity without long-range phase coherence in real space,which is remarkably similar to the high-T_(c) cuprate superconductors.These results provide a new perspective to understanding the origin of superconductivity in iron-based superconductors.

关 键 词：iron-based superconductor two-dimensional properties electronic correlation carrier doping scanning tunneling microscopy/spectroscopy 

分 类 号：O511.3[一般工业技术—材料科学与工程]