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 ab-plane one is relatively small in BaFe₂As₂ 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 Sr₂ScFePO₃ we find a very large value, γ_λ\\gtrsim200, comparable to that in strongly anisotropic high-T_c cuprate Bi₂Sr₂CaCu₂O_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.