期刊
NANO RESEARCH
卷 14, 期 11, 页码 3921-3925出版社
TSINGHUA UNIV PRESS
DOI: 10.1007/s12274-021-3316-0
关键词
CaKFe4As4; scanning tunneling microscopy; atomic resolution; density functional theory
类别
资金
- National Key Research and Development Program of China [2019FZA3004, 2017YFA0303002, 2016YFA0300202, 2019YFA0308500, 2018YFA0305800]
- National Natural Science Foundation of China [51922011, 51991340, 61888102]
- Strategic Priority Research Program of Chinese Academy of Sciences [XDB28000000]
- Funds for the Central Universities
CaKFe4As4, a new type of iron-based superconductor, shows promise as a platform for observing Majorana zero modes. Using scanning tunneling microscopy/spectroscopy, two types of surface structures were identified, providing insight for future studies on the surface of iron-pnictide superconductors.
As a new type of iron-based superconductor, CaKFe4As4 has recently been demonstrated to be a promising platform for observing Majorana zero modes (MZMs). The surface of CaKFe4As4 plays an important role in realizing the MZM since it hosts superconducting topological surface states. However, due to the complicated crystal structure, the terminal surface of CaKFe4As4 has not been determined yet. Here, by using scanning tunneling microscopy/spectroscopy (STM/S), we find that there are two types of surface structure in CaKFe4As4. Bias-dependent atomic resolution images show an evolvement from root 2 x root 2 superstructure with respect to the As lattice into 1 x 1 when the tip is brought close to the surface, revealing the sublattice of missing As atoms. Together with the first-principles calculations, we show that the surface As layer has a buckled structure. Our findings provide insight to future surface study of CaKFe4As4 as well as other iron-pnictide superconductors.
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