A new Majorana platform in an Fe-As bilayer superconductor

Wenyao Liu; Lu Cao; Shiyu Zhu; Lingyuan Kong; Guangwei Wang; Michał Papaj; Peng Zhang; Ya-Bin Liu; Hui Chen; Geng Li; Fazhi Yang; Takeshi Kondo; Shixuan Du; Guang-Han Cao; Shik Shin; Liang Fu; Zhiping Yin; Hong-Jun Gao; Hong Ding

doi:10.1038/s41467-020-19487-1

A new Majorana platform in an Fe-As bilayer superconductor

Nat Commun. 2020 Nov 10;11(1):5688. doi: 10.1038/s41467-020-19487-1.

Authors

Wenyao Liu^{1

2}, Lu Cao^{1

2}, Shiyu Zhu^{1

2}, Lingyuan Kong^{1

2}, Guangwei Wang³, Michał Papaj⁴, Peng Zhang⁵, Ya-Bin Liu⁶, Hui Chen^{1

2}, Geng Li^{1

2}, Fazhi Yang^{1

2}, Takeshi Kondo⁵, Shixuan Du^{1

7}, Guang-Han Cao⁶, Shik Shin⁵, Liang Fu⁴, Zhiping Yin³, Hong-Jun Gao^{8

9

10}, Hong Ding^{11

12

13

14}

Affiliations

¹ Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China.
² School of Physical Sciences, University of Chinese Academy of Sciences, 100190, Beijing, China.
³ Department of Physics and Center for Advanced Quantum Studies, Beijing Normal University, 100875, Beijing, China.
⁴ Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
⁵ Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan.
⁶ Department of Physics, Zhejiang University, 310027, Hangzhou, China.
⁷ CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, 100190, Beijing, China.
⁸ Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China. hjgao@iphy.ac.cn.
⁹ School of Physical Sciences, University of Chinese Academy of Sciences, 100190, Beijing, China. hjgao@iphy.ac.cn.
¹⁰ CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, 100190, Beijing, China. hjgao@iphy.ac.cn.
¹¹ Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China. dingh@iphy.ac.cn.
¹² School of Physical Sciences, University of Chinese Academy of Sciences, 100190, Beijing, China. dingh@iphy.ac.cn.
¹³ CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, 100190, Beijing, China. dingh@iphy.ac.cn.
¹⁴ Songshan Lake Materials Laboratory, 523808, Dongguan, Guangdong, China. dingh@iphy.ac.cn.

Abstract

Iron-chalcogenide superconductors have emerged as a promising Majorana platform for topological quantum computation. By combining topological band and superconductivity in a single material, they provide significant advantage to realize isolated Majorana zero modes. However, iron-chalcogenide superconductors, especially Fe(Te,Se), suffer from strong inhomogeneity which may hamper their practical application. In addition, some iron-pnictide superconductors have been demonstrated to have topological surface states, yet no Majorana zero mode has been observed inside their vortices, raising a question of universality about this new Majorana platform. In this work, through angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy measurement, we identify Dirac surface states and Majorana zero modes, respectively, for the first time in an iron-pnictide superconductor, CaKFe₄As₄. More strikingly, the multiple vortex bound states with integer-quantization sequences can be accurately reproduced by our model calculation, firmly establishing Majorana nature of the zero mode.

Abstract

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