Influence of O2 and N2 addition on the perpendicular magnetic anisotropy of Gd-Co amorphous films

Abstract

The influence of the introduction of oxygen gas and nitrogen gas into the chamber during deposition on the perpendicular magnetic anisotropy of Gd-Co amorphous films deposited by ion beam sputtering has been investigated. The films deposited without O2 and N2 addition show perpendicular magnetization in the vicinity of compensation composition. However, the perpendicular anisotropy of them is much smaller than that of the films deposited by rf sputtering. When sputtering ion energy, deposition rate, and Ar pressure are 0.5∼3 keV, 19∼30 Å/min, and 8×10−3∼8×10−2 Pa, respectively, the films obtained have almost the same perpendicular anisotropy. On the other hand, the incorporation of oxygen in the films leads to a remarkable increase of perpendicular anisotropy. The films deposited at O2 pressure of 1.6×10−3 Pa have an effective perpendicular anisotropy constant K⊥(K⊥ = Ku-2πMs2) of about 5×105 erg/cm3, where Ku is 1.1×106 erg/cm3. On the contrary, the incorporation of nitrogen decreases the perpendicular anisotropy. The incorporation of oxygen and nitrogen leads to the considerable shift of compensation composition to the Gd rich region and phase separation. These results may be attributable to preferential oxidization and nitrification of Gd.