Magnetic properties in some sputtered RCo2 amorphous alloys (R = rare-earth = Er, Sm, Tb)

The magnetic properties have been investigated in some RCo2 amorphous alloys presenting highly anisotropic magnetic systems. The magnetization process, at different temperatures, have been studied over a wide magnetic field range (up to 10 T) and temperature range (10-300 K) using a vibrating sample magnetometer (VSM). Samples with various compositions have been annealed at different temperatures. The most important results are: (1) heat treatment and composition affect the shape of hysteresis loops with high coercive forces, large high field susceptibility even up to high magnetic field confirming the sperimagnetic structure, (2) Rayleigh laws have been validated, when it is possible, for both amorphous and nanocrystallised samples but a deviation is observed in the very weak fields. This deviation can be explained by the importance of magnetostatic effects and magnetostriction.