Elastic Properties of DySb near the Magnetic and Structural Phase Transition

The shear elastic constants $c_{\theta }=\frac{(c_{11}-c_{12})}{2}$ and $c_{44}$ have been measured in DySb. $c_{44}$ shows a small softening of about 0.6% at the phase transition, while $c_{\theta }=\frac{(c_{11}-c_{12})}{2}$ exhibits a 58% drop. The large change in $c_{\theta }=\frac{(c_{11}-c_{12})}{2}$ occurs over a temperature range of more than 200 °K. The dominant mechanism for the softening of the elastic constant $c_{\theta }=\frac{(c_{11}-c_{12})}{2}$ is a Jahn-Teller strain coupling. Strong-biquadratic pair interactions are present which compete with the strain coupling.