We develop a new method of investigation of low-temperature electron relaxation in metals, based on the analysis of the temperature dependences of the attenuation of zero sound excited by ultrasonic pulses. We have discovered that these dependences obtained in the temperature region about of 1-8 K reproduce directly the temperature behavior of the electron scattering rate. The main features of our method are its insensitivity to small-angle scattering and the additivity of contributions of various relaxation processes to the total scattering rate. Both the theoretical analysis of zero-sound propagation in various damping regimes and special experiments produced for gallium confirm the validity of our consideration. We have identified the considerable contribution of electron-electron collisions in all investigated metals (gallium, aluminum, molybdenum, and tungsten) in the whole studied temperature interval and established the dominating role of Umklapp processes in the zero-sound damping at T > -4 K for gallium and most probably for tungsten. We interpret the latter result as the first experimental observation of Peierls' exponent in polyvalent metals in zero magnetic field. The values obtained for electron-electron and electron-phonon scattering rates are compared with known experimental data and theoretical estimations.

At zero magnetic field we have observed an electromagnetic radiation from superconductors subjected by a transverse elastic wave. This radiation has an inertial origin, and is a manifestation of the acoustic Stewart-Tolman effect. The effect is used for implementing a method of measurement of an effective Magnus force in type II superconductors. The method does not require the flux flow regime and allows to investigate this force for almost the whole range of the existence of the mixed state. We have studied behavior of the gyroscopic force in nonmagnetic borocarbides and Nb. It is found that in borocarbides the sign of the gyroscopic force in the mixed state is the same as in the normal state, and its value (counted for one vortex of unit length) has only a weak dependence on the magnetic field. In Nb the change of sign of the gyroscopic force under the transition from the normal to the mixed state is observed.

In the excitation of a vortex lattice in the mixed phase of Yb6 single crystals by an elastic wave, the dynamic response is found to have a negative component quadratic in the frequency; we associate this component with the vortex mass. The value of the effect is in catastrophic contradiction with the existing theoretical estimates.