Nonlinear and Hysteretic Ultrasound Propagation in Solid ${}^4$He: Dynamics of Dislocation Lines and Pinning Impurities

Izumi Iwasa, Harry Kojima

We report on the measurements of 9.6 MHz ultrasound propagation down to 15 mK in polycrystalline quantum solid ${}^4$He containing 0.3 and 20 ppm ${}^3$He impurities. The attenuation a…