Magnetic properties of Mn doped crystalline and amorphous Ge thin films grown on Si (111)

We investigated the effects of crystalline order on the structural and magnetic properties of ultrathin Mndoped Ge thin films grown by thermal diffusion. The dopant motion which occurs during the annealing stage appears to differ considerably depending upon whether the Ge layer is in a crystalline or an amorphous state. The details of the temperature-dependent magnetization curves reveal that the a-MnGe and c-MnGe films show ferromagnetic property up to 300K and ~250K, respectively. Ferromagnetic Mn5 Ge3 thin film with weakly anisotropic in-plane magnetization is formed on amorphous Ge thin film, while weakly ferromagnetic Mn5 Gex Si3−x nanostructures are developed on crystalline Ge thin film due to diffusion of Mn atoms through the Ge layer and interact with Si substrate.