抄録
The longitudinal and transverse elastic constants of polycrystalline SmRu4P12 have been measured as a function of temperature in the magnetic field up to 12 T. The transverse elastic constant shows a weak softening toward low temperatures. Both longitudinal and transverse elastic constants show a large anomaly below the metal–insulator transition TMI=16 K. These elastic anomalies indicate the ground state of the crystalline electric field multiplet to be Γ8, and that the quadrupole ordering is responsible for this metal insulator transition. The successive anomalies of SmRu4P12 have been clearly observed by ultrasonic measurements. An elastic anomaly was found at T*, which is 14 K in the absence of a magnetic field. TMI increases and T* decreases under the application of the magnetic field. The anomaly at T* is markedly enhanced by the application of a magnetic field.
