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.
| Original language | English |
|---|---|
| Article number | 5688 |
| Journal | Nature Communications |
| Volume | 11 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2020 |
Funding
We thank technical assistance from Y.-B. Huang, S.-Y. Gao, and J.-R. Huang on \u201CDreamline\u201D synchrotron-based ARPES measurements and D.-W. Shen and Z.-C. Jiang on BL03U synchrotron-based ARPES measurements. This work at IOP is supported by grants from the National Natural Science Foundation of China (11888101, 61888102, 51991340), Chinese Academy of Sciences (XDB28000000, XDB07000000), the Ministry of Science and Technology of China (2016YFA0202300, 2019YFA0308500, and 2018YFA0305800), and Beijing Municipal Science & Technology Commission (No. Z191100007219012). The band calculations used high-performance computing clusters at BNU in Zhuhai and the National Supercomputer Center in Guangzhou, and Z.Y. is supported by NSFC (11674030), the Funds for the Central Universities (310421113), and the National Key Research and Development Program of China (2016YFA0302300). L.F. is supported by US DOE (DE-SC0019275). Laser ARPES work was supported by the JSPS KAKENHI (Grant Nos. JP18H01165, JP19F19030, and JP19H00651). G.-H.C. is supported by Funds for the Central Universities and the National Key Research and Development Program of China (2019FZA3004, 2017YFA0303002, and 2016YFA0300202).