A theory of correlation between the elastic and magnetic properties of transition-metal based ferromagnetic glassy alloys is developed. The specific Young's modulus, $\frac{E}{\rho }$, is shown to be related to the thermal average of the effective spin, $〈S〉$, as $\frac{E}{\rho }=V_E^{}{}_{}{}^{02}+K{〈S〉}^2$, where $E$ and $\rho$ are Young's modulus and the density, respectively, and $V_E^{}{}_{}{}^{02}$ and $K$ are constants related to the properties of the materials. The change of $\frac{E}{\rho }$ with composition in ${\left({\mathrm{Fe}}_{1-x}{M}_x\right)}_{80}{B}_{20}$ glasses ($M$ representing Co or Ni) agrees well with the present model.

• Received 12 July 1976

DOI:https://doi.org/10.1103/PhysRevLett.37.1004