Template engineering of Co-doped BaFe2As2 single-crystal thin films

TL;DR

This paper introduces a novel template engineering method using single-crystal intermediate layers to produce high-quality epitaxial Co-doped BaFe2As2 superconducting thin films with improved properties.

Contribution

The study demonstrates a new template engineering approach with SrTiO3 and BaTiO3 layers that significantly enhances epitaxial growth and superconducting performance of ferropnictide thin films.

Findings

Achieved zero resistivity Tc of 21.5K in films

Superconducting critical current density Jc of 4.5 MA/cm2

Enhanced c-axis flux pinning and epitaxial quality

Abstract

Understanding new superconductors requires high-quality epitaxial thin films to explore intrinsic electromagnetic properties, control grain boundaries and strain effects, and evaluate device applications. So far superconducting properties of ferropnictide thin films appear compromised by imperfect epitaxial growth and poor connectivity of the superconducting phase. Here we report novel template engineering using single-crystal intermediate layers of (001) SrTiO3 and BaTiO3 grown on various perovskite substrates that enables genuine epitaxial films of Co-doped BaFe2As2 with high transition temperature (zero resistivity Tc of 21.5K), small transition widths (delta Tc = 1.3K), superior Jc of 4.5 MA/cm2 (4.2K, self field) and strong c-axis flux pinning. Implementing SrTiO3 or BaTiO3 templates to match the alkaline earth layer in the Ba-122 with the alkaline earth-oxygen layer in the templates opens new avenues for epitaxial growth of ferropnictides on multi-functional single crystal substrates. Beyond superconductors, it provides a framework for growing heteroepitaxial intermetallic compounds on various substrates by matching interfacial layers between templates and thin film overlayers.