Temperature insensitivity of Fermi surface in electron-doped high-temperature FeSe films on SrTiO3

We have performed high-resolution angle-resolved photoemission spectroscopy study of electron-doped multilayer FeSe films on SrTiO3. We determined the evolution of the electronic structure in a wide temperature range and found temperature-insensitive nature of the Fermi surface in contrast to the strong temperature dependence observed in non-doped FeSe. Such a striking doping dependence would provide a key to understanding the origin of unconventional fermiology and physical properties in FeSe.