Changing the magnetism of amorphous FeSiB by mechanical milling

We have studied the magnetic properties of a sample obtained by high-energy mechanical milling from a ferromagnetic FeSiB amorphous ribbon. The milled material mainly consists of a Fe-based amorphous matrix embedding a minor fraction of alpha-Fe nanocrystallites (~23%), and magnetization dynamics effects characterize the magnetic behavior. In particular, a magnetic transition occurs at T ~ 50 K, from a low temperature disordered collective frozen state, similar to a spin-cluster-glass, to a high temperature regime where ferromagnetism predominates. The phenomenon has been ultimately ascribed to the local modification of the interatomic distance distribution in the amorphous matrix, induced by milling.