Elastic and magnetoelastic properties of polycrystalline rare-earth-iron Laves compounds

Ultrasonic-sound velocity measurements have been used in order to determine the elastic moduli of polycrystalline rare-earth-iron Laves compounds $R{\mathrm{Fe}}_2$ ($R=\mathrm{Ce}, \mathrm{Gd}, \mathrm{Tb}, \mathrm{Dy}, \mathrm{Dy}, \mathrm{Ho}, \mathrm{Er}$) and Y${\mathrm{Fe}}_2$ between 4.2 and 300 K. The $\Delta E$ effect of these compounds was determined in external magnetic field up to 25 kOe. No saturation was reached at this field in Dy${\mathrm{Fe}}_2$ and Tb${\mathrm{Fe}}_2$. The anomalies in the elastic behavior of Ce${\mathrm{Fe}}_2$ and Ho${\mathrm{Fe}}_2$ were interpreted in terms of changes occurring in their magnetic structure. The results reveal the high sensitivity of the elastic constants to such changes.