Search

Cu and Mn co-doped LiNbO 3 films were deposited on Si (111) substrates by rf-magnetron sputtering. XRD shows a randomly oriented polycrystalline R3C structure of LiNbO 3 was formed in the films annealed at 1000 °C for 1 h in air. XPS and XAFS determine that Mn 2+ substitutes on the Li site with a Li vacancy and Cu 2+ substitutes on the Nb site with an oxygen vacancy in the LiNbO 3 lattice. SQUID measurements indicate that all the films exhibit room temperature ferromagnetism, attributed to a strong d–d electron interaction between Mn and Nb and the bound magnetic polarons resulting from the oxygen vacancies. The saturated magnetization increases but the atom magnetic moment decreases with increasing Cu content in the films. The drop of the atom magnetic moment may arise from the antiferromagnetic coupling among adjacent Cu ions and an antiparallel configuration between Cu 2+ ions and their trapped electrons. [ABSTRACT FROM AUTHOR]

The SiC/Cu nano-multilayer films were deposited on Si substrates using radio frequency and direct current alternative sputtering technique. In this paper, the transport and magnetic properties of the films were investigated. XRR shows the SiC/Cu periodical structures of the films. XRD confirms that the 3C-SiC crystal structure is formed in the films without heating substrates. The XPS indicates that the Cu atoms substitute for Si sites of the SiC lattice and exist in a mixed valance state of Cu + and Cu 2+ . The best fitting for the plots of ln ρ versus T −1/4 using the combination of the Mott and the band gap VRH models suggests that the carriers in the films are strongly localized. The films have a typical semiconductor characteristic and an obvious room temperature ferromagnetism which should arise from the bond magnetic polarons. The maximum values of saturation magnetization and carrier concentration are up to 15.2 emu/cm 3 and 1.86E + 22/cm 3 respectively. [ABSTRACT FROM AUTHOR]