Ultrasonic Absorption at Low Temperatures Subject to the Fermi Liquid Correlation of Electrons

Abstract

At low temperatures, ultrasonic absorption in metals is determined by the interaction of waves with conduction electrons. In the framework of the phenomenological theory, ultrasonic absorption in normal metals taking into account the Fermi liquid correlation of electrons is studied. It is assumed that the degenerate electron liquid is close to the equilibrium state and the spatial inhomogeneity scale 1/q (q is the ultrasonic wave vector) is larger than the mean free path of the conduction electrons. It is found that, taking into account the Fermi liquid correlations, the absorbed ultrasonic energy additionally contains terms (1 + ηL), where ηL are the second- and third-order moments of an effective interaction between electrons. Estimates of ηL show that the contribution of the liquid effects can be significant.