Magnetic properties of Fe/sub 1.2/Ti/sub 0.8/O/sub 3//Fe/sub 2/O/sub 3/ bilayered films

Abstract

Hematite-ilmenite (/spl alpha/-Fe/sub 2/O/sub 3/-FeTiO/sub 3/) solid solution system is one of the candidates for high-temperature magnetic semiconductors. The intermediate composition, Fe/sub 1.2/T/sub 0.8/O/sub 3/, is known to have the maximum saturation magnetization at low temperature. We have successfully prepared well-crystallized Fe/sub 1.2/Ti/sub 0.8/O/sub 3/ and Fe/sub 1.2/Ti/sub 0.8/O/sub 3//Fe/sub 2/O/sub 3/ bilayered films by using reactive helicon plasma sputtering. The Fe/sub 1.2/Ti/sub 0.8/O/sub 3/ films without Fe/sub 2/O/sub 3/ layers showed lower T/sub C/ of about 200 K, while the T/sub C/ of Fe/sub 1.2/Ti/sub 0.8/O/sub 3/ layers in the bilayered films increased to about 220 K. The bilayered films had a sharp interface between Fe/sub 1.2/Ti/sub 0.8/O/sub 3/ and /spl alpha/-Fe/sub 2/O/sub 3/. The strong magnetic coupling between two layers seemed to increase the T/sub C/ of the attached Fe/sub 1.2/Ti/sub 0.8/O/sub 3/ layers.