Interfaces between Fe-Chalcogenide thin films and insulators: impact on structure, magnetism, and superconductivity (IntSup)


We propose to study the influence of selected interface materials on the electronic properties of quasi-2D FeCh (Ch = Se, Te) systems. Our motivation is the recently discovered but unexplained superconducting phase at high temperatures ~100K in tensile strained FeSe on SrTiO3, one order of magnitude higher than in bulk FeSe. Thin FeCh layers will be grown by molecular beam epitaxy on selected substrates (bottom interfaces) ranging from semiconductors, to normal (fluorides and oxides) and topological insulators, all with particular electrical properties and different lattice constants, causing different interface charge transfers and FeCh tensile strains. We will characterize structure, magnetism, and electronic properties of FeCh sample systems among others by scanning tunneling microscopy, magnetotransport, magneto-optical methods, and photoelectron spectroscopy. As a second concept we would like to explore the potential of oxide overlayer growth (top interfaces), which - from application points of view - is of interest as passivation layers on FeCh for future ex-situ devices.