Investigations of the electronic structures of metals using ultrasonic techniques

This paper reviews ultrasonic research on the electronic properties of metals performed since the first observations, about ten years ago, that at low temperatures electrons are responsible for the primary contribution to the ultrasonic attenuation. After a description of the Fermi surface and other aspects of the physics of electrons in metals, there is a sketch of the origins of geometric resonances, acoustic cyclotron resonances, and quantum oscillations, as well as other less familiar magnetoacoustic effects in the ultrasonic attenuation in pure metals. The types of information that each of these effects can give about the Fermi surface are cited. Then there is a discussion of ultrasonic attenuation experiments in superconductors, and of the kinds of information that these experiments can provide. In each area, the present status of research is indicated. The paper concludes with a brief description of the experimental techniques involved in this branch of research. Included are some relatively new techniques for performing simultaneous experiments at several ultrasonic frequencies and for performing ultrasonic attenuation experiments in metals at 9 Gc/s.