Ion-Beam Synthesis of Structure-Oriented Iron Nanoparticles in Single-Crystalline Rutile TiO₂

Magnetic nanoparticles embedded into semiconductors have current perspectives for use in semiconducting spintronics. In this work, 40 keV Fe+ ions were implanted in high fluences of (0.5 ÷ 1.5) × 1017 ion/cm2 into an oxide semiconductor and single-crystalline TiO2 plates of rutile structure with (100) or (001) face orientations. Microstructure, elemental-phase composition, and magnetic properties of the Fe-ion-implanted TiO2 were studied by scanning and transmission electron microscopies (SEM and TEM), X-ray photoelectron (XPS) and Rutherford backscattering (RBS) spectroscopies, as well as vibrating-sample magnetometry (VSM). The high-fluence ion implantation results in the formation of magnetic nanoparticles of metallic iron beneath the irradiated surface of rutile. The induced ferromagnetism and observed two- or four-fold magnetic anisotropy are associated with the endotaxial growth of Fe nanoparticles oriented along the crystallographic axes of TiO2