Recent progress of Majorana zero mode in iron-based superconductors

In this talk I will report our recent progress of Majorana zero mode in iron-based superconductors. Following our original findings of superconducting topological surface state [1] and Majorana zero mode (MZM) [2] of Fe(Te, Se), we have recently observed a half-integer level shift of vortex bound states [3] and quantized Majorana conductance [4] in this material, which are hallmarks of MZMs. In addition, we have also found that most of iron-based superconductors [5], including monolayer Fe(Te, Se)/STO [6], have similar topological electronic structures. One of them, CaKFe₄As₄, an Fe-As bilayer superconductor (Tc ~ 35K), is found to possess MZM and other bound states that can be well reproduced by a simple theoretical model [7]. Our observations offer a new, robust platform for realizing and manipulating MZMs, which may be used for quantum computing at a relatively high temperature.

References
[1] Peng Zhang et al., “Observation of topological superconductivity on the surface of iron-based superconductor”, Science 360, 182 (2018)
[2] Dongfei Wang et al., “Evidence for Majorana bound state in an iron-based superconductor”, Science 362, 334 (2018)
[3] Lingyuan Kong et al., “Observation of half-integer level shift of vortex bound states in an iron-based superconductor”, Nature Physics, doi/10.1038/ s41567-019-0630-5
[4] Shiyu Zhu et al., “Observation of Majorana conductance plateau by scanning tunneling spectroscopy”, arXiv:1904.06124
[5] Peng Zhang et al., “Multiple topological states in iron-based superconductors”, Nature Physics 15, 41 (2019)
[6] Xun Shi et al., Science Bulletin 62, 503 (2017)
[7] Wenyao Liu et al., “A new Majorana platform in an Fe-As bilayer superconductor”, arXiv:1907.00904