Influenced of Fe buffer thickness on the crystalline quality and the transport properties of Fe/Ba(Fe1-xCox)2As2 bilayers

TL;DR

This study investigates how varying the thickness of an Fe buffer layer affects the crystalline quality and superconducting transport properties of Fe/Ba(Fe1-xCox)2As2 bilayers, revealing optimal conditions for high critical current density.

Contribution

It demonstrates that increasing Fe buffer thickness improves crystalline quality and superconducting performance in Fe/Ba-122 bilayers, providing guidance for optimizing epitaxial growth.

Findings

Thicker Fe buffer layers (15 nm) lead to higher critical current density (Jc)

Thinner Fe buffers (4 nm) result in lower Jc due to grain boundary effects

Well-textured growth correlates with improved superconducting properties

Abstract

The implementation of an Fe buffer layer is a promising way to obtain epitaxial growth of Co-doped BaFe2As2 (Ba-122). However, the crystalline quality and the superconducting properties of Co-doped Ba-122 are influenced by the Fe buffer layer thickness, dFe. The well-textured growth of the Fe/Ba-122 bilayer with dFe = 15 nm results in a high Jc of 0.45 MAcm$^{-2}$ at 12 K in self-field, whereas a low Jc value of 61000 Acm$^{-2}$ is recorded for the bilayer with dFe = 4 nm at the corresponding reduced temperature due to the presence of grain boundaries.