The magnetization of ${\mathrm{Fe}}_{80}{\mathrm{B}}_{20-x}{\mathrm{C}}_x \left(0\mathrm{}\le x\le 8\right)$ ferromagnetic metallic glasses has been measured in the temperature range $0<T\lesssim 180$ K (corresponding to $0<\mathrm{}\frac{T}{T_C}\lesssim 0.3$) and in magnetic fields up to 40 kOe. As in crystalline ferromagnets, the magnetization obeys the equation $\frac{\Delta \sigma \mathrm{}\left(T\right)\mathrm{}}{\sigma \mathrm{}\left(0\right)\mathrm{}}=\beta T^{\frac{3}{2}}+\gamma T^{\frac{5}{2}}$. For the first time a clear necessity for the coefficient $\gamma$ even at lowest temperatures has been found in an amorphous series through bulk magnetization measurements. The concentration ($x$) dependence of the spin-wave stiffness constant $D$ is discussed. The range of exchange interactions in this amorphous series is of the order of 2 atomic distances, i.e., less than that in crystalline nickel.

• Received 6 January 1983

DOI:https://doi.org/10.1103/PhysRevB.27.5618