Preparation and characterization of epitaxial ilmenite-hematite films.

The solid solution system ilmenite-hematite [(FeTiO3)1-x–(Fe2O3)x] is a potential candidate for applications in spintronics due to its intrinsic ferrimagnetic and semiconducting properties. Epitaxial ilmenite-hematite films with x=0.33, which have the highest room temperature magnetic moment, were grown on α-Al2O3 (0001) substrates using pulsed laser deposition technique with varying oxygen partial pressure in the ambient gas. Structural, magnetic, electrical, and optical properties are found to be largely dependent on the oxygen content of the films which is controlled by substrate temperature and ambient gas composition. The highest crystalline and magnetic ordering and the lowest resistivity values could be obtained for growth at high temperatures and under low oxygen pressure. A narrowing of the band gap (to around 2.4 eV) was observed for films grown under high oxygen pressure in comparison with films grown in vacuum or argon (around 3.3 eV). [ABSTRACT FROM AUTHOR]