Magnetic Properties of Compositionally Modulated Nd-Co Thin Films

A series of compositionally modulated Nd-Co thin films was prepared by UHV evaporation. The modulated structure and composition of the films were studied by X-ray diffraction measurement and energy-dispersive X-ray microanalysis, respectively. Magnetization and anisotropy measurements were carried out using a vibrating sample magnetometer in the temperature range between 77 K and room temperature. A coherent structure was found over the modulation length ¿ (20 Å ¿ ¿ ¿ 70 Å). The magnetization of films with an atomic ratio of Nd:Co = 1:3 changed slightly with ¿, but the perpendicular anisotropy energy decreased significantly with increasing ¿. The reduction of the anisotropy energy seems to be due to a decrease in the proportion of atoms which are adjacent to the interfaces between Nd and Co layers.