6 research outputs found
Effect of Structural Parameters on Superconductivity in Fluorine-Free LnFeAsO1-y (Ln=La,Nd)
The crystal structure of LnFeAsO (Ln = La, Nd) has been studied by
the powder neutron diffraction technique. The superconducting phase diagram of
NdFeAsO is established as a function of oxygen content which is
determined by Rietveld refinement. The small As-Fe bond length suggests that As
and Fe atoms are connected covalently. FeAs-tetrahedrons transform toward a
regular shape with increasing oxygen deficiency. Superconducting transition
temperatures seem to attain maximum values for regular FeAs-tetrahedrons
Fermi surface in BaNiP
We report measurements of the de Haas-van Alphen (dHvA) oscillation and a
band structure calculation for the pnictide superconductor BaNiP, which
is isostructural to BaFeAs, the mother compound of the iron-pnictide
high- superconductor (BaK)FeAs. Six dHvA-frequency
branches with frequencies up to 8 kT were observed, and they are in
excellent agreement with results of the band-structure calculation. The
determined Fermi surface is large, enclosing about one electron and hole per
formula unit, and three-dimensional. This is in contrast to the small
two-dimensional Fermi surface expected for the iron-pnictide high-
superconductors. The mass enhancement is about two.Comment: To appear in J. Phys. Soc. Jpn., Vol. 78, No.