Structural analysis and transport properties of [010]-tilt grain boundaries in Fe(Se,Te)

Understanding the nature of grain boundaries is a prerequisite for fabricating high-performance superconducting bulks and wires. For iron-based superconductors [e.g. Ba(Fe,Co) $$ As $$ , Fe(Se,Te), and NdFeAs(O,F)], the dependence of the critical current density $$ on misorientation angle ( $$ ) has been explored on [001]-tilt grain boundaries, but no data for other types of orientations have been reported. Here, we report on the structural and transport properties of Fe(Se,Te) grown on CeO $$ -buffered symmetric [010]-tilt roof-type SrTiO $$ bicrystal substrates by pulsed laser deposition. X-ray diffraction and transmission electron microscopy revealed that $$ of Fe(Se,Te) was smaller whereas $$ of CeO $$ was larger than that of the substrate. The difference in $$ between the CeO $$ buffer layer and the substrate is getting larger with increasing $$ . For $$ of the substrates, $$ of Fe(Se,Te) was zero, whereas $$ of CeO $$ was continuously increasing. The inclined growth of CeO $$ can be explained by the geometrical coherency model. The $$ -axis growth of Fe(Se,Te) for $$ of the substrates is due to the domain matching epitaxy on (221) planes of CeO $$ . Electrical transport measurements confirmed no reduction of inter-grain $$ for $$ , indicative of strong coupling between the grains.