Study of the acoustic de Haas effect by the ultrasonic measurements

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The de Haas effect of the oscillatory magnetization is a method to observe the Fermi surface of metallic compounds. The acoustic de Haas effect by the measurement of the sound velocity and attenuation coefficient is a unique method to determine the electron-lattice interaction in the itinerant electron system. In the present project, we focus on the precise measurement of the sound velocity as a function of the magnetic field at low temperatures. In the case of the heavy Fermion system, the measurements in the extreme condition with low temperature and high magnetic field is required to detect the quantum oscillation due to the Landau state in field. In the last three years, we have developed an low-temperature ultrasonic system with a superconducting magnet up to 180kOe and a dilution refrigerator down to 10mK. The top-loading probe of the dilution refrigerator is equipped by a gonio meter for sample rotation and coaxial lines for high frequency measurement. For the first cooling, we measured a typical example of the heavy Fermion systems CeRuィイD22ィエD2SiィイD22ィエD2, which has been grown by Prof. Onuki. Above the metamagetic transition of 80kOe, the quantum oscillation of the longitudinal CィイD211ィエD2 mode has been clearly detected below 600mK down to 20mK. The effective mass of the branch is 3.5m0. The ultrasonic measurement system in low temperature and high magnetic field in Niigata University is the most excellent apparatus for the investigation of the Fermi surface of the heavy Fermion system, the quadrupolar effect of 4f- and 3d-elecron compounds and the charge fluctuation effect in the mixed valence compounds. Our ultrasonic system is opened for cooperative works with many scientist in the world.