2 research outputs found
Pairing mechanism in Fe pnictide superconductors
By applying an exact unitary transformation to a two-band hamiltonian which
also includes the effects due to large pnictogen polarizabilities, we show that
an attractive spin-mediated Hubbard term appears in the ,
nearest-neighbour channel. This pairing mechanism implies a singlet
superconducting order parameter in iron pnictides.Comment: 4 pages, 3 figure
Low-temperature synthesis of SmFeAsO0.7F0.3 wires with high transport critical current density
Ag-sheathed SmFeAsO0.7F0.3 (Sm-1111) superconducting wires were prepared by a
one-step solid state reaction at temperatures as low as 850~900C, instead of
commonly used temperatures of 1150~1250C. The X-ray diffraction pattern of the
as-sintered samples is well indexed on the basis of tetragonal ZrCuSiAs-type
structure. We characterized transport critical current density Jc of the
SmFeAsO0.7F0.3 wires in increasing and subsequently decreasing fields, by a
resistive four-probe method. A transport Jc as high as ~1300 A/cm^2 at 4.2 K
and self field has been observed for the first time in Sm-1111 type
polycrystalline superconductors. The Jc also shows a rapid depression in small
applied fields as well as a magnetic-history dependence, indicating weak-linked
grain boundaries. The low-temperature synthesis method can be very beneficial
to fabricating the RE-1111 iron oxynictides in a convenient and safe way.Comment: 12 pages, 3 figure