Preparation and structural characterization of FeCo epitaxial thin films on insulating single-crystal substrates

FeCo epitaxial films were prepared on MgO(111), SrTiO3(111), and Al2O3(0001) single-crystal substrates by ultrahigh vacuum molecular beam epitaxy. The effects of insulating substrate material on the film growth process and the structures were investigated. FeCo(110)(bcc) films grow on MgO substrates with two type domains, Nishiyama-Wassermann (NW) and Kurdjumov-Sachs (KS) relationships. On the contrary, FeCo films grown on SrTiO3 and Al2O3 substrates include FeCo(111)(bcc) crystal in addition to the FeCo(110)(bcc) crystals with NW and KS relationships. The FeCo(111)(bcc) crystal consists of two type domains whose orientations are rotated around the film normal by 180 degrees each other. The out-of-plane and the in-plane lattice spacings of FeCo(110)(bcc) and FeCo(111)(bcc) crystals formed on the insulating substrates are in agreement with those of the bulk Fe50Co50 (at. %) crystal with small errors ranging between + 0.2% and + 0.4%, showing that the strains in the epitaxial films are very small. (C) 2010 American Institute of Physics. [doi:10.1063/1.3334200]