Magneto-volume effect of Fe-based amorphous ferromagnetic alloys

The magneto-volume effect of Fe-based amorphous alloys has been studied by making a systematic study of the thermal expansion and magnetic properties of (Fe x M 1-x ) 85 N 15 where M=Cr, Mn, Co and Ni. It has been found that the magneto-volume effect, omega m , is a simple function of the effective 3d electron number N eff with the calculation based on the charge transfer model with a maximum at N eff =8.2, where the spontaneous magnetisation also reaches a maximum. It has also been found that the ratio of the spin-wave stiffness constant obtained by neutron scattering, D s , to that estimated from the temperature dependence of magnetisation, D m , exhibits the same N eff dependence as omega m , thus providing clear experimental evidence that the deviation of D s from D m in Fe-based amorphous alloys is due to the Invar effect.