Frequency dependence of ultrasound attenuation in II-type superconductor

It has been theoretically shown that ultrasound attenuation due to magnetic vortices in type II superconductor exhibits local temperature and frequency maxima. The absolute maximum occurs at frequency corresponding to that for thermally activated vortex hopping. It was shown that vortex elasticity gives rise an additional solution of wave equation that significantly manifests itself in the case of strong surface pinning. For different surface pinning conditions the impedances of acoustic resonator were calculated.