An EXAFS and XANES study of Fe doped TiO2 films

RODRÍGUEZ TORRES, C.E, CABRERA A.F., ERRICO, L.A., FERNÁNDEZ VAN RAAP, M.B., SÁNCHEZ, F.H., DUHALDE, S. AND VIGNOLO, M.F.

LNLS, Campinas, Brasil

Workshop; 15ª Reunión Anual de Usuarios del LNLS; 2005

Laboratorio Nacional de Luz Sincrotron

Recent advances in the spintronic technology have stimulated considerable interest in ferromagnetic semiconductors with high Curie temperature for the development of innovative spintronic devices. Examples of such materials are Co-doped TiO2 and Mn-doped GaAs [1, 2]. Following theoretical calculations wich predict ferromagnetic behaviour of Ti1��xFexO2 [3], we have studied the local environment surrounding Fe atoms in films of Ti0:9Fe0:1O2 obtained by pulsed laser deposition on LaAlO3. XANES and EXAFS have been used to determine changes in valence and in the environment of Fe as a function of growth parameters. Transparent films were obtained when deposition was performed at high O2 pressure (between 2��4x10��4 mbar). In these films XANES demonstrated that Fe is in the +3 valence state and EXAFS measurements indicated that Fe environment is similar to that of Fe in maghemite. Dark films were obtained at low O2 pressure (between 2��10x10��5 mbar). In this case XAFS results showed that Fe is predominantly in metallic a-iron-like arrangements.Co-doped TiO2 and Mn-doped GaAs [1, 2]. Following theoretical calculations wich predict ferromagnetic behaviour of Ti1��xFexO2 [3], we have studied the local environment surrounding Fe atoms in films of Ti0:9Fe0:1O2 obtained by pulsed laser deposition on LaAlO3. XANES and EXAFS have been used to determine changes in valence and in the environment of Fe as a function of growth parameters. Transparent films were obtained when deposition was performed at high O2 pressure (between 2��4x10��4 mbar). In these films XANES demonstrated that Fe is in the +3 valence state and EXAFS measurements indicated that Fe environment is similar to that of Fe in maghemite. Dark films were obtained at low O2 pressure (between 2��10x10��5 mbar). In this case XAFS results showed that Fe is predominantly in metallic a-iron-like arrangements. 1. Y. Matsumoto, M. Murakami, T. Shono, T. Hasegawa, T. Fukumura, M. Kawasaki, P. Ahmet, t. Chikyow, S. Koshihara, H. Koinuma, Science 291, 854 (2001). 2. S.A. Chambers, S.Thevuthasan, R.F.C. Farrow, R.F. Marks, J.U. Thiele, L. Folks, M.G. Samant, A.J. Kellock, N. Ruzycki, D.L. Ederer, U. Diebold, . Appl. Phys. Lett. 79, 3467 (2001). 3. L. A. Errico, M. Weissmann, and M. Rentería , Phys.Stat. Sol. (2004) in press.