FeTe$_{1-x}$Se$_{x}$ monolayer films: towards the realization of high-temperature connate topological superconductivity

摘要

We performed angle-resolved photoemission spectroscopy studies on a series ofFeTe$_{1-x}$Se$_{x}$ monolayer films grown on SrTiO$_{3}$. Thesuperconductivity of the films is robust and rather insensitive to thevariations of the band position and effective mass caused by the substitutionof Se by Te. However, the band gap between the electron- and hole-like bands atthe Brillouin zone center decreases towards band inversion and parity exchange,which drive the system to a nontrivial topological state predicted bytheoretical calculations. Our results provide a clear experimental indicationthat the FeTe$_{1-x}$Se$_{x}$ monolayer materials are high-temperature connatetopological superconductors in which band topology and superconductivity areintegrated intrinsically.