8 research outputs found
Striking Zn impurity effect on the Fe-based superconductor BaFe1.87Co0.13As2
Nonmagnetic impurity effect was studied on the n-type Fe-based superconductor
BaFe1.87Co0.13As2 (Tc = 25 K) by a successful Zn substitution for Fe up to 7
at.%. Magnetic susceptibility, electrical resistivity, specific heat, and Hall
coefficient measurements indicated that Tc linearly decreases with the Zn
concentration and disappears at 7 at.%. The result is quantitatively comparable
with what was observed for YBCO, while it disagrees with a recent report for
the p-type Ba0.5K0.5Fe2As2. Fragile SC against a nonmagnetic impurity was first
confirmed for the n-type 122 Fe-based superconductor.Comment: 14 pages, 5 figure
Critical temperature of an anisotropic superconductor containing both nonmagnetic and magnetic impurities
The combined effect of both nonmagnetic and magnetic impurities on the
superconducting transition temperature is studied theoretically within the BCS
model. An expression for the critical temperature as a function of potential
and spin-flip scattering rates is derived for a two-dimensional superconductor
with arbitrary in-plane anisotropy of the superconducting order parameter,
ranging from isotropic s-wave to d-wave (or any pairing state with nonzero
angular momentum) and including anisotropic s-wave and mixed (d+s)-wave as
particular cases. This expression generalizes the well-known Abrikosov-Gor'kov
formula for the critical temperature of impure superconductors. The effect of
defects and impurities in high temperature superconductors is discussed.Comment: 4 eps figure