Versatile fluoride substrates for Fe-based superconducting thin films

TL;DR

This study demonstrates the successful growth of Co-doped BaFe2As2 thin films on various fluoride substrates via pulsed laser deposition, achieving epitaxial films with notable superconducting transition temperatures despite lattice mismatch.

Contribution

It introduces a versatile method for growing Fe-based superconducting thin films on fluoride substrates, expanding substrate options and understanding interface reactions.

Findings

Epitaxial growth achieved on fluoride substrates despite large lattice mismatch.

Superconducting transition temperature around 27 K on CaF2.

Comparable crystalline quality and superconducting properties to films on MgO.

Abstract

We demonstrate the growth of Co-doped BaFe2As2 (Ba-122) thin films on AEF2 (001) (AE: Ca, Sr, Ba) single crystal substrates using pulsed laser deposition. All films are grown epitaxially despite of a large misfit of -10.6% for BaF2 substrate. For all films a reaction layer is formed at the interface confirmed by X-ray diffraction and by transmission electron microscopy. The superconducting transition temperature of the film on CaF2 is around 27 K, whereas the corresponding values of the other films are around 21 K. The Ba-122 on CaF2 shows identical crystalline quality and superconducting properties as films on Fe-buffered MgO.