Observation Of The Anisotropic Dirac Cone In The Band Dispersion Of 112-Structured Iron-Based Superconductor Ca0.9la0.1feas2

CaFeAs2 is a parent compound of recently discovered 112-type iron-based superconductors. It is predicted to be a staggered intercalation compound that naturally integrates both quantum spin Hall insulating and superconducting layers and an ideal system for the realization of Majorana modes. We performed a systematical angle-resolved photoemission spectroscopy and first-principles calculation study of the slightly electron-doped CaFeAs2. We found that the zigzag As chain of 112-type iron-based superconductors play a considerable role in the low-energy electronic structure, resulting in the characteristic Dirac-cone like band dispersion as the prediction. Our experimental results further confirm that these Dirac cones only exist around the X but not Y points in the Brillouin zone, breaking the S-4 symmetry at iron sites. Our findings present the compelling support to the theoretical prediction that the 112-type iron-based superconductors might host the topological non-trivial edge states. The slightly electron doped CaFeAs2 would provide us a unique opportunity to realize and explore Majorana fermion physics. Published by AIP Publishing.