Crystal texture-dependent magnetic and magnetotransport properties of half-metallic Fe3O4 films grown on oxidized Si substrates by reactive deposition

Abstract

Nanocrystalline magnetite (Fe3O4) films with various preferred crystallite orientations were grown on oxidized silicon surface by reactive iron deposition in an oxygen atmosphere. Depending on the partial pressure of oxygen (PO2), the evolution of the structural, magnetic, and magnetotransport properties of the grown films was investigated. We found that the growth of films containing only the Fe3O4 phase occurs in a certain PO2 range, and the magnetite crystallites may have (311) or (110) preferred orientation. It was revealed that films with (311) and (110) textures have a column structure. An increase in the PO2 leads to a structure transformation from (311) to (110) texture with larger crystallites. A film with (110) texture showed higher values of saturation magnetization, magnetoresistance and spin polarization. The analysis of approach to magnetic saturation revealed that the local magnetic anisotropy of crystallites in textured films is much higher than the anisotropy of bulk magnetite due to the large surface contribution. The FORC diagram method in combination with the approach to magnetic saturation proved the existence of the exchange coupling between large and small grains. Our results open the reliable route for crystal texture-depending manipulation of functional properties of thin magnetite films for advanced spintronic applications.