Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Dilute magnetic oxides using the electron spin rather than its charge as information carrier are expected to play a key role in the development of spinelectronics. As it has been shown recently, indium oxide (IO), a transparent conducting material, is of potential importance also as a material for spintronics. Polycrystalline and amorphous (ca. 300 nm thick) n-type conductive IO films were grown on SiO₂/Si substrates using reactive magnetron sputtering. The films were implanted with Cr⁺ ions in order to reach Cr concentrations of 1, 2, 3, 4 and 5 at%. The implantation energy was 120 keV. Cr is chosen as a dopant because of its large magnetic moment in the ionic state, and the antiferomagnetic nature of Cr metal segregations. It is non-trivial to form any ferromagnetic secondary phase of Cr oxide. Highly oxygen deficient 2%Cr:IO co-evaporated films revealed ferromagnetism. Here we study the effect of the post-growth treatment on the structural, electrical, magnetic, and optical properties of Cr-implanted IO films. It is shown that only the 2%Cr:IO implanted film is weakly ferromagnetic at 5 K. A reasonable model for the Cr:IO implanted films has been developed to extract optical constants from spectroscopic ellipsometry data below 3 eV in dependence on the Cr concentration.