Mössbauer Study of Fe/Nd Artificial Superstructure Films

Multilayered films with artificial superstructures were prepared by alternate deposition of Fe and Nd in ultrahigh vacuum. Individual layer thicknesses of Fe and Nd layer were varied from 7 Å to 52 Å and 3 Å to 46 Å, respectively. From 57 Fe Mössbauer measurements, the direction of Fe magnetic moments for the samples [Fe(26∼39 Å)/Nd(7∼14 Å)] is found to be nearly perpendicular to the film plane both at 300 K and 4.2 K. In contrast, for the samples [Fe(26∼52 Å)/Nd(28∼46 Å)], the direction at 300 K is in-plane but changes to the perpendicular direction at low temperature. The relationship between the perpendicular magnetic anisotropy and the magnetization of interface Nd atoms is discussed.