Ablation replacement of iron with Co, Mn, Ni, and Cu during growth of iron-based superconductor films in the Fe-0.9 M Se-0.1(0.92) system

Artikel i vetenskaplig tidskrift, 2014

Thin films of iron-based chalcogenide superconductors FeSe0.92, with iron partially replaced (at least up to 10 at %) by elements such as cobalt, nickel, manganese, or copper, have been grown on the surface of LaAlO3 crystals. Growth is performed by the laser ablation of a target prepared in the form of a ceramic pellet by high-temperature synthesis and the sintering of preliminarily pressed stoichiometric mixture of powders. Iron in these ceramics is replaced with an alloying metal by no more than 3 at %. The rest (7 at %) of the metal is in the form of precipitates of other phases. X-ray diffraction analysis of the grown films has shown that they are single-crystal and free of any precipitates of other crystallographic orientations and phases. This is evidence of the complete (10 at %) replacement of iron with a doping metal in the film structure. This circumstance indicates that the synthesis of components occurs more actively and completely during laser ablation (than in solid-phase chemical reactions) as a result of the transformation of multicomponent target material into plasma. Thus, one can fabricate film materials in a wider range of chemical compositions than in the form of solid-phase synthesized ceramics.