Iron-oxide interlayer existing in Ba-ferrite/sapphire(001) films grown by sputtering

Abstract

We revealed the existence of a very thin (similar to 50 Angstrom thick) epitaxial. iron-oxide interlayer in amorphous Ba-ferrite thin films on sapphire(001) using synchrotron x-ray scattering. Depending on the sputtering gases used in radio frequency sputtering deposition, two different iron-oxide interlayers were formed; non-magnetic alpha-Fe2O3 interlayer by pure Ar gas and ferromagnetic Fe3O4 interlayer by Ar-10% O-2 gas mixture. The alpha-Fe2O3 interlayer much more promoted the crystallization of amorphous Ba-ferrite, compared to the Fe3O4 interlayer. We suggest that the interlayer existing between amorphous Ba-ferrite and sapphire substrate greatly contributes to the reduction of the activation energy for the crystallization of amorphous Baferrite film.