Influence by trajectorial electron transport on anomalous ultrasound   attenuation in high pure Gallium single crystal
  The anomalous propagation of longitudinal ultrasound with the frequencies of 70 and 150 MHz in the high pure Gallium single crystal at the weak external magnetic field (the magnetic field H perpendicular to the wave vector k) at the low temperature of 0.4 K was researched experimentally. The delayed ultrasonic signal, comparing to the main ultrasonic signal, is detected. The research on the new magneto-acoustic effects made it possible to find the temperature dependence of the frequency of collisions between the electrons and the thermal phonons in the high pure Gallium single crystal. It is found that the anomalous oscillations of propagation velocity of ultrasonic signal pulses and the signals, propagating by the way of the electron transport in the high pure type I superconductor, can be detected at the directions of the magnetic field H close to the magnetic field H parallel to the wave vector k. 
Anatoly G. Shepelev, Oleg P. Ledenyov and Genady D. Filimonov
cond-mat.supr-con cond-mat.mtrl-sci physics.ins-det