Magnetism of thin amorphous Fe-Gd films before and after annealing

Amorphous 5000 Å thick films of FexGd100 - x (x = 66, 69, 71, 72, 77, 78) were investigated by both transmission (TMS) and conversion-electron (CEMS) Mössbauer spectroscopy. The results show that the average magnetic hyperfine field is perpendicular to the plane of the film; its strength and direction do not change with depths decreasing to 300 Å. However, the CEMS spectra indicate that there are several phases near the surface which are not present in the rest of the film. One of the phase is identified as an oxide, with a hyperfine field of 45 T. After annealing two of the samples, it is shown for the first time that increases in the bulk saturation magnetization and decreases in the average perpendicular anistropy result from the crystallization of nearly pure α-Fe. The remnant amorphous phase retains the perpendicular anistropy observed for as-prepared films. © 1985.