High-Field Ultrasonic Study of CeIrIn${}_5$

We performed ultrasonic and temperature measurements under pulsed magnetic fields on CeIrIn${}_5$ to investigate whether or not the origin of metamagnetic transition and field-induced Lifshitz transition was described by the anisotropic electronic ordering with crystal symmetry breaking. We observed elastic anomalies with the negative magnetocaloric effects around the field-induced Lifshitz transition and the metamagnetic transition. On the other hand, the elastic anomalies appeared both in the transverse elastic constants $(C_{11}-C_{12})\mathrm{/}2$ and $C_{66}$ in CeIrIn${}_5$ while $(C_{11}-C_{12})\mathrm{/}2$ showed significant elastic anomaly at the crystal symmetry breaking fields in CeRhIn${}_5$. These results indicate that the anisotropic electronic ordering with crystal symmetry breaking is absent in high-magnetic fields in CeIrIn${}_5$.