ИСТИНА

The discovery of high-temperature (Tc) superconductivity up to 100 K in a monolayer FeSe on SrTiO3 has caused a variety of disputes on how superconductivity evolves in such materials from bulk to film, because bulk FeSe exhibits a Tc not higher than 10 K. Moreover, for multilayer FeSe charge carrier doping convert non-superconducting films with various thicknesses into superconductors with Tc up to 48 K. In order to predict changes of electronic structure leading to Tc increase we need to carefully describe electronic structure of low-dimensional iron chalcogenides and understand mechanisms of charge-transfer in such systems. In this work we investigate a change of electronic structure during the transition from bulk material to two-dimensional one for iron chalcogenides (FeSe, FeTe, for 1, 2, 3, 4, 5, 10, 15 layers and bulk material) with ab initio calculations. All calculations were performed using projector augmented plane-wave (PAW) method with PBE exchange correlation potential. Our results present systematization of electronic structure data for bulk and low-dimensional iron chalcogenides. The reported study was funded by RFBR according to the research project No.16-32-00435 мол_a.