6,018 research outputs found
Superconductivity and Magnetism in REFeAsO1-xFx (RE=Rare Earth Elements)
Fluoride-doped iron-based oxypnictides containing rare-earth gadolinium
(GdFeAsO0.8F0.2) and co-doping with yttrium (Gd0.8Y0.2FeAsO0.8F0.2) have been
prepared via conventional solid state reaction at ambient pressure. The
non-yttrium substituted oxypnictide show superconducting transition as high as
43.9 K from temperature dependent resistance measurements with the Meissner
effect observed at a lower temperature of 40.8 K from temperature dependent
magnetization measurements. By replacing a small amount of gadolinium with
yttrium Tc was observed to be lowered by 10 K which might be caused by a change
in the electronic or magnetic structures since the crystal structure was not
altered.Comment: 4 pages, 4 figures, Journal of Physics: Conference Series
(Proceedings in the LT25 Low Temperature Physics Conference) Submitte
Upper critical fields and critical current density of BaFe2(As0.68P0.32)2 single crystal
The transport properties, upper critical fields, superconducting anisotropy,
and critical current density in an iso-valent phosphorus-doped BaFe2As2 single
crystal close to optimum doping are investigated in this report. Temperature
dependent resistivity and susceptibility show a superconducting transition
temperature, Tc, just below 31 K both with sharp transitions. The upper
critical field parallel to the ab-plane, Hc2^ab, is above 77 Tesla while that
along the c-axis direction, Hc2^c, is just above 36 Tesla, yielding a low
superconducting anisotropy ratio ~ 2. The estimated inter-plane coherence
length based on the Ginzburg-Landau (G-L) theory indicates BaFe2(As0.68P0.32)2
is still above the point for a dimensional crossover inferring the
superconducting layers are not weakly-coupled in this system. The critical
current density at 5 K obtained from magnetization loops measurement show a
modest Jc as high as 10^5 A/cm2.Comment: 13 pages, 5 figure
Nanoscopic coexistence of magnetic and superconducting states within the FeAs layers of CeFeAsO1-xFx
We report on the coexistence of magnetic and superconducting states in
CeFeAsO1-xFx for x=0.06(2), characterized by transition temperatures T_m=30 K
and T_c=18 K, respectively. Zero and transverse field muon-spin relaxation
measurements show that below 10 K the two phases coexist within a nanoscopic
scale over a large volume fraction. This result clarifies the nature of the
magnetic-to-superconducting transition in the CeFeAsO1-xFx phase diagram, by
ruling out the presence of a quantum critical point which was suggested by
earlier studies.Comment: 4 pages, 3 figs, accepted for publication as PRB Rapid com
Molecular structure of highly-excited resonant states in Mg and the corresponding Be+O and C+C decays
Exotic Be and C decays from high-lying resonances in Mg are
analyzed in terms of a cluster model. The calculated quantities agree well with
the corresponding experimental data. It is found that the calculated decay
widths are very sensitive to the angular momentum carried by the outgoing
cluster. It is shown that this property makes cluster decay a powerful tool to
determine the spin as well as the molecular structures of the resonances.Comment: 17 pages, no figur
Improving the economic value of photographic screening for optical coherence tomography-detectable macular oedema : a prospective, multicentre, UK study
Peer reviewedPublisher PD
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