Oscillatory Striction and Electron-Lattice Interaction

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The quantum oscillation of the elastic constant of metallic compounds at low temperature as a function of applied field is called as the acoustic de Haas effect. This is an excellent probe to determine the electron-lattice interaction of the conduction electron system, which is related to the BCS mechanism of superconductivity. Goto has established the experimental method of the acoustic de Haas effect at low temperatures by 3He cryostat and dilution refrigerator. The sample length of metallic compounds also showes the quantum oscillation at low temperatures. This is called as the oscillatory magneto-striction, which is also originated from the electron-lattice interaction on the Fermi surface. In the present research project we have studied the acoustic de Haas effect by the ultrasonic velocity as well as the magneto-striction. We have done a development of the apparatuse for the oscillatory magneto-striction based on the capacitance measrement with a capacitance bridge. The capacitan … More ce method is excellent for the low temperature measurements because the capacitance bridge provides an ideal prove with quite small input power. Furthermore the highly resolution of capacitance bridge leads an accurate measurement of the oscillatory intensity which is related to the electron-lattice coupling. In this project we developed the capacitance cell, which may control sample orientation along applied magnetic fields inside the superconducting magnet. In the present project we made the magneto-striction apparatus for the 3He cryostat, but more sophisticated system for the dilution refrigerator is still remained to be developed.The investigation of the acoustic de Haas effect on the low carrier compounds on rare earth monopnictides, CeBi, LaBi, LaAs and uranium compound USb were performed intensively in this project. The observation of the heavy hole surface beta4 in Ce Bi gave an evidence for the p-f mixing mechanism in the system. The oscillation intensity of the acoustic de Haas effect on LaAs and LaBi shows that the electron-lattice interaction of the longitudinal sound wave containing the volume strain in low carrier compounds is enhanced considerably. This is an very important result relating to the electron correlation in the low carrier system. Less