A New Phenomenon is Sound Attenuation in Bismuth under Very Strong Magnetic Fields

Abstract

A new phenomenon in sound attenuation in bismuth has been observed at liquid helium temperatures and under very strong magnetic-field conditions such that the electrons and holes in the states with the Landau quantum number n=1 almost simultaneously satisfy resonance when varing the field strength in some suitable field directions. The anomalous part of the attenuation at the resonance field position, Δα, obeys the law Δα=A(T⁄T_c−1)^{−(0.49±0.06)} in a limited region of reduced temperature (T⁄T_c−1). The values of the parameters T_c(\lesssim1.6 K) and A depend characteristically on the difference between the resonance field strengths for the electrons and holes. The experimental facts suggest that this phenomenon may be related to the fluctuation of electron-hole pairs produced above the excitonic phase transition temperature.