Importance of the Fermi surface and magnetic interactions for the superconducting dome in electron-doped FeSe intercalates

摘要

The van-der-Waals gap of iron chalcogenide superconductors can be intercalated with a variety of inorganic and organic compounds that modify the electron doping level of the iron layers. In Li-x(C3N2H10)(0.37)FeSe, a dome in the superconducting transition temperature T-c has been reported to occur in the doping range of x = 0.06 to x = 0.68. We use a combination of density functional theory and spin fluctuation theory to capture the evolution of superconducting transition temperatures theoretically. We clearly demonstrate how the changing electronic structure supports an increasing superconducting T-c. The suppression of T-c at high doping levels can, however, only be understood by analyzing the magnetic tendencies, which evolve from stripe-type at low doping to bicollinear at high doping.