Annealing and Substrate Bias Effects on Perpendicular Magnetic Anisotropy in GdFe and TbFe Sputtered Films

Abstract

GdFe and TbFe films sputtered with substrate bias voltage (V_B) have been annealed both in air and in vacuum at temperatures up to 300°C In the case of annealing in air the oxidation occurs at the film surface and forms an oxidized layer that has in-plane magnetization,and therefore, the perpendicular anisotropy (K_u) decreases. Crystallographic structure of the films changes from the amorphous state into crystal-like one with increasing V_B. The amorphous films sputtered with low V_B oxidize more readily than the crystal-like films. Consequently the films sputtered with low V_B show a larger decrease in K_u than those with high V_B. Annealing in vacuum does not seem to change the film properties.