$J_{\rm c}$ Scaling and Anisotropies in Co-Doped Ba-122 Thin Films

We have successfully grown epitaxial, superconducting films of Ba(Fe
_1-x
Co
_x
)
₂
As
₂
(Ba-122)with
x
~ 0.1. The films grow without observable correlated defects parallel to the c-axis, as confirmed by TEM. This is also reflected in the absence of a c-axis peak in
J
_c
(θ). In contrast to cuprate high-
T
_c
superconductors such as YBa
₂
Cu
₃
O
_7-δ
or even Bi
₂
Sr
₂
Ca
₂
Cu
₃
O
_10-δ
, the pnictides show a rather low anisotropic behavior in their
J
_c
(θ) behavior as well as in their upper critical fields,
H
_c2
. As a multiband superconductor, Ba-122 exhibits a temperature dependent electronic mass anisotropy.