Structural and magnetic characterization of Fe 0.3Ti 0.7O 2−δ films obtained by pulsed laser deposition

Abstract

We present a study of crystalline structure, local environment around the magnetic atoms and magnetic behaviour of Fe 0.3Ti 0.7O 2− δ films, produced by Pulsed Laser Deposition, as a function of oxygen pressure and substrate temperature. Dark films were obtained by deposition at low O 2 pressure (between 2×10 −3 and 10 −2 Pa). These films are ferromagnetic with coercivities around 0.03–0.04 T. Fe atoms are found to be predominantly metallic Fe. Transparent films were obtained when deposition was performed at high O 2 pressure (between 4 and 20 Pa). Fe atoms are mainly in +3 valence state. These films have a component magnetically ordered probably corresponding to α-Fe(Ti) 2O 3 and a paramagnetic one attributed to Fe substituted anatase. After a thermal treatment Fe changes to +2 valence state and α-Fe(Ti) 2O 3 orders in the ilmenite phase increasing ten times the saturation magnetization of the magnetically ordered (hysteretic) component.