Chemical reaction between BaFe2(As,P)2 superconducting thin film and LSAT substrate

• BaFe2(As0.67P0.33)2 (Ba122:P) thin films were fabricated on LSAT substrates by a PLD method.
• Superconducting Ba122:P thin films with c-axis orientation and in-plane alignment were successfully obtained.
• XRD investigation suggested the existence of some apatite-type phase.
• TEM observation revealed the formation of a reacted layer between the film and the substrate.
• Discussion on the relationship between the lattice parameters, P content and Tc was made.

BaFe2(As0.67P0.33)2 (Ba122:P) thin films were fabricated on (LaAlO3)0.3–(SrAl0.5Ta0.5O3)0.7 (LSAT) (1 0 0) substrates by a pulsed laser deposition method using a second-harmonic Nd:YAG laser. Superconducting Ba122:P thin films with c-axis orientation and in-plane alignment were successfully obtained. Detailed structural properties on the films were investigated by X-ray diffraction. The X-ray pattern suggested the existence of some apatite-type phase. Transmission electron microscope observation revealed the formation of a reacted layer between the film and the substrate. The reacted layer had a Ba(Sr)-rich and P-rich composition. These analyses indicated the formation of an apatite material at the interface of the film and the substrate.