Fast dissipative and diffusional relaxation of the magnetic permeability in ferromagnetic metallic glasses

Abstract

A strong relaxation of the a.c. magnetic permeability is observed in amorphous ferromagnets at very short times (t < 10⁻²s) after impulse demagnetization. Such a relaxation is shown to be composed of two contributions of different natures and characteristics; a change in the energy dissipated by the oscillating domain walls, and a much smaller diffusive after-effect, similar to that usually observed at longer times after demagnetization. A method to observe this second contribution is proposed and discussed.