Fe1+yTexSe1- x: A Delicate and Tunable Majorana Material

Here, we report the observation for the pz electron band and the band inversion in Fe1 + yTexSe1–x with angle-resolved photoemission spectroscopy. Furthermore, we found that excess Fe (y > 0) inhibits the topological band inversion in Fe1 + yTexSe1 – x, which explains the absence of Majorana zero modes in previous reports for Fe1+yTexSe1 – x with excess Fe. Based on our analysis of different amounts of Te doping and excess Fe, we propose a delicate topological phase in this material. Thanks to this delicate phase, one may be able to tune the topological transition via applying lattice strain or carrier doping.