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

TL;DR

This study uses first-principles calculations to analyze the anisotropy in iron-based superconductors, revealing potential for power applications and novel Josephson effects based on their anisotropic properties.

Contribution

It provides the first detailed first-principles analysis of anisotropy in iron-based superconductors, linking anisotropy ratios to their suitability for applications and Josephson effects.

Findings

BaFe2As2 and LiFeAs have small anisotropy ratios (~3), suitable for transport applications.

Sr2ScFePO3 exhibits very high anisotropy (~200), enabling intrinsic Josephson junctions.

Potential for novel Josephson effects due to multi-gap superconductivity.

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 $\gamma_\lambda$ of the c-axis penetration depth to the ab-plane one is relatively small in BaFe2As2 and LiFeAs, i.e., $\gamma_\lambda \sim 3$, 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, $\gamma_\lambda \sim 200$, comparable to that in strongly anisotropic high-Tc cuprate Bi2Sr2CaCu2O{8-\delta}. 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.