Thickness variation of the magnetic anisotropy in DyFe thin films using magneto-optical techniques

Magneto-optical measurements of the anisotropy of homogeneous Dy ₁₈Fe₈₂ films as a function of thickness (134.0-13.4 nm) confirm that the perpendicular anisotropy disappears when films are less than 60 nm thick. Since, the range of films exhibits both out of plane and in-plane anisotropy, both the polar Kerr effect and the transverse Kerr effect were used to determine the anisotropy. At about 60 nm the perpendicular anisotropy K_⊥⩽ the shape anisotropy (K_s=2πM_s²)