Structure of spin excitations in heavily electron-doped Li0.8Fe0.2ODFeSe superconductors.

ABSTRACT: Heavily electron-doped iron-selenide high-transition-temperature (high-T c) superconductors, which have no hole Fermi pockets, but have a notably high T c, have challenged the prevailing s ± pairing scenario originally proposed for iron pnictides containing both electron and hole pockets. The microscopic mechanism underlying the enhanced superconductivity in heavily electron-doped iron-selenide remains unclear. Here, we used neutron scattering to study the spin excitations of the heavily electron-doped iron-selenide material Li0.8Fe0.2ODFeSe (T c?=?41?K). Our data revealed nearly ring-shaped magnetic resonant excitations surrounding (?, ?) at ?21?meV. As the energy increased, the spin excitations assumed a diamond shape, and they dispersed outward until the energy reached ?60?meV and then inward at higher energies. The observed energy-dependent momentum structure and twisted dispersion of spin excitations near (?, ?) are analogous to those of hole-doped cuprates in several aspects, thus implying that such spin excitations are essential for the remarkably high T c in these materials.The microscopic mechanism underlying an enhanced superconductivity in electron-doped iron selenide superconductor remains unclear. Here, Pan et al. report the spin excitations of Li0.8Fe0.2ODFeSe, revealing analogous momentum structure and dispersion to hole-doped cuprates.

SUBMITTER: Pan B 

PROVIDER: S-EPMC5527112 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature