Ac magnetic susceptibility studies on the Dy0.73Tb0.27Fe2-xNix and Ho0.85Tb0.15Fe2-yNiy intermetallics

A.c. magnetic susceptibility measurements were carried out on the intermetallic compounds Dy0.73Tb0.27Fe2-xNix and Ho0.85Tb0.15Fe2-yNiy [x = y = 0-2] in the temperature range 14-300 K. Several anomalies were observed in the temperature variation of the a.c. susceptibility for various samples. These are identified as the transitions due to spin reorientation and Curie temperature. In the case of x = y = 1.5, the transition due to Curie temperature is observed in the form of a step, and in the case of x = y = 2.0 this transition is observed as a sharp peak. This behaviour is attributed to the role played by the magnetic anisotropy below the Curie temperature.