Preparation of Amorphous Gd-Fe Perpendicular Magnetic Films The Composition Distribution in the Films Prepared by a Single Source Evaporation

Abstract

Amorphous Gd-Fe thin films were prepared by a vacuum evaporation using a single source containing a mixture of gadolinium and iron. The films have a uniform perpendicular anisotropy. The composition distribution normal to the film was calculated. Suitable conditions for preparing the Gd-Fe thin films were determined.
In order to calculated the composition distributi on in the film, the relationship between the evaporation fraction and the mole ratio of iron to gadolinium in the vapor was discussed using the Raoult's law and the Langmuir's equation. The initial charge of the source was 0.2 g and the initial concentration of iron in the source was 50 mol%. Four kinds of films were prepared at different deposit time. And the composition of these films was measured by EPMA (electron probe microanalyzer). The following results were obtained.
The measured ratio of iron to gadolinium in these films varied from 4.8 to 0.9, as th e evaporation fraction changed from O.07 to 0.32. The calculated values of the ratios were larger than the measured ones, and the average of the differences between the calculated values and the measured ones was 44% of the calculated values.
This corresponds to 59 mol% gadolinium in the film. A perpen dicular magnetic anisotropy was well observed reproducibly in the films which were deposited when convection between iron and gadolinium occured sufficiently in the melt.