First-principles study for the anisotropy of iron-based superconductors toward power and device applications

Nakamura, Hiroki  ; Machida, Masahiko  ; Koyama, Tomio*; Hamada, Noriaki*

Performing the first-principles calculations, we investigate the anisotropy in the superconducting state of iron-based superconductors to gain an insight into their potential applications. The anisotropy ratio of the -axis penetration depth to the -plane one is relatively small in BaFeAs and LiFeAs, i.e., , indicating that the transport applications are promising in these superconductors. On the other hand, in those having perovskite type blocking layers such as SrScFePO we find a very large value, , comparable to that in strongly anisotropic high- cuprate BiSrCaCuO. Thus, the intrinsic Josephson junction stacks are expected to be formed along the -axis, and novel Josephson effects due to the multi-gap nature are also suggested in these superconductors.