471 research outputs found
Effect of disorder outside the CuO planes on of copper oxide superconductors
The effect of disorder on the superconducting transition temperature
of cuprate superconductors is examined. Disorder is introduced into the cation
sites in the plane adjacent to the CuO planes of two single-layer
systems, BiSrLnCuO and
LaNdSrCuO. Disorder is controlled by changing
rare earth (Ln) ions with different ionic radius in the former, and by varying
the Nd content in the latter with the doped carrier density kept constant. We
show that this type of disorder works as weak scatterers in contrast to the
in-plane disorder produced by Zn, but remarkably reduces suggesting
novel effects of disorder on high- superconductivity.Comment: 5 pages, 5 figures, to be published in Phys. Rev. Let
Momentum-Resolved Ultrafast Electron Dynamics in Superconducting Bi2Sr2CaCu2O8+delta
The non-equilibrium state of the high-Tc superconductor Bi2Sr2CaCu2O8+delta
and its ultrafast dynamics have been investigated by femtosecond time- and
angle-resolved photoemission spectroscopy well below the critical temperature.
We probe optically excited quasiparticles at different electron momenta along
the Fermi surface and detect metastable quasiparticles near the antinode. Their
decay through e-e scattering is blocked by a phase space restricted to the
nodal region. The lack of momentum dependence in the decay rates is in
agreement with relaxation dominated by Cooper pair recombination in a boson
bottleneck limit
Universality of dispersive spin-resonance mode in superconducting BaFe2As2
Spin fluctuations in superconducting BaFe2(As1-xPx)2 (x=0.34, Tc = 29.5 K)
are studied using inelastic neutron scattering. Well-defined commensurate
magnetic signals are observed at ({\pi},0), which is consistent with the
nesting vector of the Fermi surface. Antiferromagnetic (AFM) spin fluctuations
in the normal state exhibit a three-dimensional character reminiscent of the
AFM order in nondoped BaFe2As2. A clear spin gap is observed in the
superconducting phase forming a peak whose energy is significantly dispersed
along the c-axis. The bandwidth of dispersion becomes larger with approaching
the AFM ordered phase universally in all superconducting BaFe2As2, indicating
that the dispersive feature is attributed to three-dimensional AFM
correlations. The results suggest a strong relationship between the magnetism
and superconductivity.Comment: 5 pages, 5 figure
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