Fe1+yTexSe1-x: a delicate and tunable Majorana material


 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. Basing 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 able to tune the topological transition via applying lattice strain or carrier doping.