First-Principles Study for the Anisotropy of Iron-Based Superconductors toward Power and Device Applications

Abstract

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 γ λ of the c -axis penetration depth to the a b -plane one is relatively small in BaFe 2 As 2 and LiFeAs, i.e., γ λ ∼3, indicating that the transport applications are promising in these superconductors. On the other hand, in those having perovskite type blocking layers such as Sr 2 ScFePO 3 we find a very large value, \(\gamma_{\lambda}\gtrsim 200\), comparable to that in strongly anisotropic high- T c cuprate Bi 2 Sr 2 CaCu 2 O 8-δ . Thus, the intrinsic Josephson junction stacks are expected to be formed along the c -axis, and novel Josephson effects due to the multi-gap nature are also suggested in these superconductors.