Observation of a Ubiquitous(π,π)-Type Nematic Superconducting Order in the Whole Superconducting Dome of Ultra-Thin BaFe_(2-x)Ni_(x)As_(2) Single Crystals  

作　　者：Yu Dong Yangyang Lv Zuyu Xu M.Abdel-Hafiez A.N.Vasiliev Haipeng Zhu Junfeng Wang Liang Li Wanghao Tian Wei Chen Song Bao Jinghui Wang Yueshen Wu Yulong Huang Shiliang Li Jie Yuan Kui Jin Labao Zhang Huabing Wang Shun-Li Yu Jinsheng Wen Jian-Xin Li Jun Li Peiheng Wu 董禹;吕阳阳;徐祖雨;M.Abdel-Hafiez;A.N.Vasiliev;朱海鹏;王俊峰;李亮;田王昊;陈伟;鲍嵩;王靖辉;吴越珅;黄裕龙;李世亮;袁洁;金魁;张蜡宝;王华兵;于顺利;温锦生;李建新;李军;吴培亨(School of Electronic Science and Engineering&School of Physics,Nanjing University,Nanjing 210093,China;National Laboratory of Solid State Microstructures,Nanjing University,Nanjing 210093,China;Collaborative Innovation Center of Advanced Microstructures,Nanjing University,Nanjing 210093,China;National University of Science and Technology(MISiS),Moscow 119049,Russia;Department of Physics and Astronomy,Box 516,Uppsala University,Uppsala SE-75120,Sweden;Moscow State University,Moscow 119991,Russia;Wuhan National High Magnetic Field Center&School of Physics,Huazhong University of Science and Technology,Wuhan 430074,China;ShanghaiTech Laboratory for Topological Physics&School of Physical Science and Technology,ShanghaiTech University,Shanghai 201210,China;Beijing National Laboratory for Condensed Matter Physics&Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;Synergetic Innovation Center in Quantum Information and Quantum Physics,University of Science and Technology of China,Hefei 230026,China)

机构地区：[1]School of Electronic Science and Engineering&School of Physics,Nanjing University,Nanjing 210093,China [2]National Laboratory of Solid State Microstructures,Nanjing University,Nanjing 210093,China [3]Collaborative Innovation Center of Advanced Microstructures,Nanjing University,Nanjing 210093,China [4]National University of Science and Technology(MISiS),Moscow 119049,Russia [5]Department of Physics and Astronomy,Box 516,Uppsala University,Uppsala SE-75120,Sweden [6]Moscow State University,Moscow 119991,Russia [7]Wuhan National High Magnetic Field Center&School of Physics,Huazhong University of Science and Technology,Wuhan 430074,China [8]ShanghaiTech Laboratory for Topological Physics&School of Physical Science and Technology,ShanghaiTech University,Shanghai 201210,China [9]Beijing National Laboratory for Condensed Matter Physics&Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China [10]Synergetic Innovation Center in Quantum Information and Quantum Physics,University of Science and Technology of China,Hefei 230026,China

出　　处：《Chinese Physics Letters》2021年第9期85-95,共11页中国物理快报（英文版）

基　　金：Supported by the National Natural Science Foundation of China(Grant Nos.61771234,61727805,11674157,11674158,11774152,11822405,61521001,61571219;61501222);the National Key Projects for Research and Development of China(Grant Nos.2016YFA0300401,2017YFB0503302,2017YFA0304002;2017YFB0503300);the start-up funding from ShanghaiTech University,Innovative Research Team in University(PCSIRT);the Natural Science Foundation of Shanghai Municipality(Grant No.20ZR1436100);the Science and Technology Commission of Shanghai Municipality(Grant No.YDZX20203100001438);Jiangsu Key Laboratory of Advanced Techniques for Manipulating Electromagnetic Waves,Natural Science Foundation of Jiangsu Province(Grant No.BK20180006);the Fundamental Research Funds for the Central Universities(Grant No.020414380117)。

摘　　要：In iron-based superconductors,the(0,π) or(π,0) nematicity,which describes an electronic anisotropy with a fourfold symmetry breaking,is well established and believed to be important for understanding the superconducting mechanism.However,how exactly such a nematic order observed in the normal state can be related to the superconducting pairing is still elusive.Here,by performing angular-dependent in-plane magnetoresistivity using ultra-thin flakes in the steep superconducting transition region,we unveil a nematic superconducting order along the(π,π) direction in electron-doped BaFe_(2-x)Ni_(x)As_(2) from under-doped to heavily overdoped regimes with x=0.065- 0.18.It shows superconducting gap maxima along the(π,π) direction rotated by 45° from the nematicity along(0, π) or(π,0) direction observed in the normal state.A similar(π,π)-type nematicity is also observed in the under-doped and optimally doped hole-type Ba1-yKyFe2 As_(2),with y=0.2-0.5.These results suggest that the(π,π) nematic superconducting order is a universal feature that needs to be taken into account in the superconducting pairing mechanism in iron-based superconductors.

关 键 词：PAIRING (x) Crystal 

分 类 号：O511.3[一般工业技术—材料科学与工程]