Low-temperature metal-insulator transition in the electron-doped iron chalcogenide FeSe superconductor

The normal state of the iron chalcogenide superconductors shows a range of inexplicable features. Both bad metallic resistivity, characteristic pseudogap features and proximity to insulating states mark these systems as correlated non-Fermi liquid metals. Here, using the LDA+DMFT scheme with sizable multi-orbital correlations, we show how the incoherent non-Fermi liquid metallic state of tetragonal-FeSe superconductor is inherently unstable to the specific kind of insulator seen in experiments. We describe the metal-insulator transition in electron-doped FeSe microscopically, along with implications for the low-temperature specific heat and static spin susceptibility. Copyright (C) EPLA, 2010