227 research outputs found
Determination of the pairing state in iron-based superconductors through neutron scattering
We calculate the spin susceptibility in the s_{+-} and s_{++} superconducting
states of the iron pnictides using the effective five orbital model and
considering the quasiparticle damping. For the experimentally evaluated
magnitude of the quasiparticle damping and the superconducting gap, the results
at the wave vector ~ (pi,0) show that the s_{+-} state is more consistent with
the neutron scattering experiments, while for larger quasiparticle damping and
the superconducting gap, the s_{++} state can be more consistent. To
distinguish between two cases that reproduce the experiments at the wave vector
~ (pi,0), we propose to investigate experimentally the wave vector ~ (pi,pi).Comment: 5pages, 3 figures, Accepted in Phys. Rev.
Hidden robust presence of a hole Fermi surface in a heavily electron doped iron based superconductor LaFeAs
We investigate the electronic structure of a recently discovered, heavily
electron-doped iron based superconductor LaFeAs. Although first
principles calculation shows apparent absence of hole Fermi surfaces around the
point, we reveal, by hypothetically removing the La orbital
contribution, that a hole Fermi surface around the point is
essentially present. In the collapsed phase of LaFeAs, which is
non-superconducting, the hole Fermi surface is found to be absent, and the
difference from the uncollapsed superconducting phase can be naturally
understood within the spin-fluctuation mediated pairing scenario.Comment: 6 pages, 4 figure
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