44 research outputs found
Pressure Study of BiS2-Based Superconductors Bi4O4S3 and La(O,F)BiS2
We report the electrical resistivity measurements under pressure for the
recently discovered BiS2-based layered superconductors Bi4O4S3 and La(O,F)BiS2.
In Bi4O4S3, the transition temperature Tc decreases monotonically without a
distinct change in the metallic behavior in the normal state. In La(O,F)BiS2,
on the other hand, Tc initially increases with increasing pressure and then
decreases above ? 1 GPa. The semiconducting behavior in the normal state is
suppressed markedly and monotonically, whereas the evolution of Tc is
nonlinear. The strong suppression of the semiconducting behavior without doping
in La(O,F)BiS2 suggests that the Fermi surface is located in the vicinity of
some instability. In the present study, we elucidate that the superconductivity
in the BiS2 layer favors the Fermi surface at the boundary between the
semiconducting and metallic behaviors.Comment: 4 pages, 6 figures, Accepted for publication in J. Phys. Soc. Jp
Fabrication of binary FeSe superconducting wires by novel diffusion process
We report successful fabrication of multi- and mono-core FeSe wires with high
transport critical current density Jc using a simple in-situ Fe-diffusion
process based on the powder-in-tube (Fe-diffusion PIT) method. The seven-core
wire showed transport Jc of as high as 1027 A/cm2 at 4.2 K. The superconducting
transition temperature Tczero was observed at 10.5 K in the wire-samples, which
is about 2 K higher than that of bulk FeSe. The Fe-diffusion PIT method is
suitable for fabricating multi-core wires of the binary FeSe superconductors
with superior properties.Comment: 14 pages, 5 figure
Tartaric acid in red wine as one of the key factors to induce superconductivity in FeTe0.8S0.2
The red wine dependence of superconductivity in FeTe0.8S0.2 was investigated.
Samples with a higher shielding volume fraction had a tendency to show a higher
concentration of tartaric acid in red wine. We found the tartaric acid is one
of the key factors to induce superconductivity in FeTe0.8S0.2.Comment: 9 pages, 4 figure