Preparation and characterization of epitaxial Fe2-xTixO3 films with various Ti concentrations (0.5 < x < 1.0)

An ilmenite-hematite solid solution ( Fe_2-xTi_xO₃ ) is one of the candidates for practical magnetic semiconductors with a high Curie temperature. We have prepared well-crystallized epitaxial Fe_2-xTi_xO₃ films with a wide range of Ti concentrations - x=0.50, 0.60, 0.65, 0.76, 0.87, and 0.94 - on α-Al₂O₃(001) substrates. The films are prepared by a reactive helicon plasma sputtering technique to evaporate Fe and TiO targets simultaneously under optimized oxygen pressure conditions. The structural characterizations of the films reveal that all films have a single phase of the ordered structure with R3 symmetry, where Ti-rich and Fe-rich layers are stacked alternately along the c axis. All films have large ferrimagnetic moments at low temperature, and room temperature magnetization is clearly observed at x<0.7. The inverse temperature dependence of the resistivities of the films indicates their semiconducting behavior. The film resistivities decrease with decreasing Ti concentration.

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This is a author's copy,as published in Journal of Applied Physics , 2008, volume 104, issue 3, Article Number: 033713.
Publisher URL: http://dx.doi.org/10.1063/1.2966298
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