On the ultrasonic absorption and dispersion in amorphous superconductors

Publisher Website
Google Scholar
Abstract
We explain the unexpected behaviour of the ultrasonic absorption observed in the amorphous superconductor Pd30Zr70. It is assumed that the relaxation of the tunnelling states present in amorphous metals, is determined by their strong coupling to electrons as well as to thermal phonons. The distribution of the corresponding coupling strengths as invoked in the tunnelling model leads to a smooth temperature dependence of the absorption when passing through the superconducting transition temperature Tc. In contrast, the dispersion should exhibit a change of slope at Tc