Coercive Force of Fe-Rare Earth Metal Amorphous Alloys

The coercive force of various kinds of Fe-rare earth metal(R) amorphous alloys prepared by high-rate dc sputtering has been investigated at low temperatures. The concentration dependence of coercive force can be explained by the random magnetic anisotropy model. Fe-Sm amorphous alloys have a ferrimagnetic-like sperimagnetic structure because the energy separation between the ground state and the excited state of Sm ion is very small. Fe-Ce and Fe-Gd amorphous alloys exhibit no large coercive force due to the valence fluctuation of Ce ion and the S-state of Gd ion, respectively. On the other hand, the coercive force of almost all other amorphous alloys is significantly large and decreases exponentially with increasing temperature. The change in the slope of logH_c vs. T plots occurs in the Fe-Sm amorphous alloys and it is concerned with ferrimagnetic-like interaction between Fe and Sm. Similar results have also been obtained by the Monte Carlo simulations