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.