The evolution of soft magnetic properties and the related density change during amorphous-nanocrystalline transformation

The frequency dependence of permeability and power loss are investigated in FINEMET samples after isothermal heat treatments, leading to structural relaxation and/or nanocrystallization. The rapid decrease in power loss and increase in permeability at low frequencies are connected mainly with the structural relaxation and the first period of nanocrystallization. The time scale for the evolution of soft magnetic properties at high frequencies is similar to that for the density change