Generic Fe buffer layers for Fe-based superconductors: Epitaxial FeSe1−<i>x</i>Te<i>x</i> thin films

Abstract

Biaxially textured FeSe1−xTex films have been realized on Fe-buffered MgO substrates by pulsed laser deposition. Similar to the Fe/BaFe2As2 bilayers, the crystalline quality of FeSe1−xTex films exhibit a sharp out-of-plane and in-plane texture less than 0.9°. The Fe/FeSe1−xTex bilayers showed high superconducting transition temperatures of over 17 K. The angular-dependent critical current densities exhibit peaks positioned at H ⊥ c similar to other pnictide thin films. The volume pinning force of FeSe1−xTex in this direction is very strong compared with that of Co-doped BaFe2As2, due to a good matching between the interlayer distance in the c direction and the out-of-plane coherence length.