Magnetoelastic softening of moduli and determination of magnetic anisotropy in RE‐TM compounds

The longitudinal elastic modulus of polycrystalline Tb.3Dy.7Fe2 shows a magnetoelastic contribution which falls between those of the two shear wave moduli reported previously, and has a strong dependence on magnetic field. The temperature dependence of these moduli at finite fields, when compared with a model of linear magnetoelastic response, yields the anisotropy field as a function of temperature in good agreement with single crystal measurements. The longitudinal velocities of GdCo2 by contrst show no dependence on magnetic field beyond 2 KOe.