Topological superconducting and Majorana zero mode in a new Fe-As bilayer superconductor

By combining the topological band structure and superconductivity, Fe-based superconductor Fe(Te,Se) is found to host a Majorana Zero Mode (MZM) inside its vortex core. However, the strong intrinsic inhomogeneity induced by the difference between Te and Se atom constraints further researching and practical application of MZM in this material. Recently, we found a Fe-As bilayer superconductor (Tc~35 K), CaKFe₄As₄, which could host the topological nontrivial surface state and homogeneous bulk meanwhile. Here I will introduce our observation in CaKFe₄As₄. Our ARPES and STM results mention that MZM and other bound states are derived from the topological surface state, which can be well reproduced by a simple theoretical model for topological superconducting, thus CaKFe₄As₄ is promising to be a new and more practical Majorana platform.