Superconductivity by hidden spin fluctuations in electron-doped iron selenide

Berg, Metlitski and Sachdev, Science 338, 1606 (2012), have shown that the exchange of hidden spin fluctuations by conduction electrons with two orbitals can result in high-temperature superconductivity copper-oxide materials. We introduce a similar model for iron-selenide superconductors are electron doped. Conduction carry minimal 3d xz yz iron-atom orbitals. Low-energy at checkerboard wavevector Q_AF from nested Fermi surfaces center corner unfolded (one-iron) Brillouin zone. Magnetic frustration super-exchange interactions via selenium atoms stabilize versus true fluctuations. At half filling, Eliashberg theory based purely on reveals Lifshitz transition to electron/hole surface pockets folded (two-iron) zone, but vanishing spectral weights. The underlying spin-density wave groundstate is therefore Mott insulator. Upon doping, finds weights hole remain vanishingly small, while larger become appreciable. This prediction consistent observation alone electron-doped iron selenide angle-resolved photoemission spectroscopy (ARPES). also an instability S+- isotropic Cooper pairs alternate sign between visible faint pockets. Comparison energy gaps observed ARPES scanning tunneling microscopy (STM) short-range magnetic order.