Effect of Ta Underlayer on Perpendicular Anisotropy of TbFeCo Films

We study Ta underlayer thickness dependence of perpendicular magnetic anisotropy (PMA) in TbFeCo films. The experiment shows that perpendicular coercivity, saturation magnetization, and remanent squareness ratio of the TbFeCo films change significantly with the Ta underlayer thickness. For example, the perpendicular coercivity (H-c) of the films increases from 671 to 2305 Oe. The reason is that the Ta underlayer affects the number of magnetic pinning sites and the oxidation of the films by residual oxygen atoms in the experimental environment.