FeTiO3/Fe2O3 Multilayered Films for New Magnetic Semiconductors above Room Temperature
Well-crystallized Fe1.18Ti0.82O3 and Fe1.18Ti0.82O3/Fe2O3 bilayered films were successfully prepared by using reactive helicon plasma sputtering technique. The solid solution films, Fe2−xTixO3, between hematite (α-Fe2O3) and ilmenite (FeTiO3) with various Ti concentrations, x, were epitaxially formed on the α-Al2O3(0001) single-crystalline substrates. The magnetic and electric properties of the solid solution films were systematically changed with increasing the Ti concentration. The film with the intermediate composition of Fe1.18Ti0.82O3 had the largest saturation magnetization at low temperature. However, the TC of solid solution films was linearly decreased with increasing the Ti concentration. The Fe1.18Ti0.82O3 film without Fe2O3 layers showed lower TC of about 200 K, while the TC of the Fe1.18Ti0.82O3/Fe2O3 bilayered film increased to about 220 K. The strong magnetic coupling between layers seemed to increase the TC of the attached Fe1.18Ti0.82O3 layer. The sharp interface between Fe1.18Ti0.82O3 and α-Fe2O3 layers was confirmed by the XPS depth profiling.
T. Fujii et al., "FeTiO3/Fe2O3 Multilayered Films for New Magnetic Semiconductors above Room Temperature", Advances in Science and Technology, Vol. 45, pp. 1309-1315, 2006