Preparation of amorphous cobalt ferrite films with perpendicular anisotropy and their magnetooptical properties

Abstract

Amorphous CoFe 2 O 4 films were made from CoFe 2 alloy and P 2 O 5 as the starting materials by the double source evaporation method. As the films were made in various levels of pressure of evaporated P 2 O 5 (P p2 o 5 ) in the bell jar, different crystal phases and perpendicular anisotropy constants (Ku) of the films were obtained. More precisely, when Pp 2 o 5 was higher than 5×10-3torr, the amorphous films were produced and under Pp 2 o 5 of higher than 10-2torr the maximum Ku of the films with the perpendicular anisotropy was 1.8×105erg/cm3. The perpendicular anisotropy seemed to be induced by both shape anisotropy with the columnar structure and uniaxial magnetic anisotropy of Co2+and Fe2+. For amorphous CoFe 2 O 4 films, the dependence of the polar Kerr rotation angle on the wave length became complicated with the increase in Pp 2 o 5 . A curve showing the relation between polar Kerr rotation angle and the wave length had a broad, positive peak in the region from 300 nm to 500 nm which was characteristic of amorphous CoFe 2 O 4 films.