267 research outputs found
Inelastic neutron scattering study on the resonance mode in an optimally doped superconductor LaFeAsOF
An optimally doped iron-based superconductor LaFeAsOF with
K has been studied by inelastic powder neutron scattering. The
magnetic excitation at \AA is enhanced below , leading to
a peak at meV as the resonance mode, in addition to the
formation of a gap at low energy below the crossover energy . The peak energy at \AA corresponds to in
good agreement with the other values of resonance mode observed in the various
iron-based superconductors, even in the high- cuprates. Although the
phonon density of states has a peak at the same energy as the resonance mode in
the present superconductor, the -dependence is consistent with the resonance
being of predominately magnetic origin.Comment: 4 pages, 5 Postscript figure
Dynamical Screening and Superconducting State in Intercalated Layered Metallochloronitrides
An essential property of layered systems is the dynamical nature of the
screened Coulomb interaction. Low energy collective modes appear as a
consequence of the layering and provide for a superconducting-pairing channel
in addition to the electron-phonon induced attractive interaction. We show that
taking into account this feature allows to explain the high critical
temperatures (Tc~26K) observed in recently discovered intercalated
metallochloronitrides. The exchange of acoustic plasmons between carriers leads
to a significant enhancement of the superconducting critical temperature that
is in agreement with the experimental observations
Microwave Penetration Depth and Quasiparticle Conductivity in PrFeAsO_1-y Single Crystals : Evidence for a Full-Gap Superconductor
In-plane microwave penetration depth and quaiparticle
conductivity at 28 GHz are measured in underdoped single crystals of the
Fe-based superconductor PrFeAsO ( K) by using a
sensitive superconducting cavity resonator. shows flat
dependence at low temperatures, which is incompatible with the presence of
nodes in the superconducting gap . The temperature dependence
of the superfluid density demonstrates that the gap is non-zero
() all over the Fermi surface. The microwave
conductivity below exhibits an enhancement larger than the coherence
peak, reminiscent of high- cuprate superconductors.Comment: 4 pages, 3 figures. Version accepted for publication in Phys. Rev.
Lett. For related results of hole-doped 122 system, see arXiv:0810.350
- …