With the introduction of bulk metallic glasses a new material class has emerged which allows for the investigation of glassy properties at very low temperatures. Besides their disordered atomic structure metallic glasses are characterized by the presence of conduction electrons which can interact with tunneling systems.
We investigated the elastic properties of a superconducting bulk metallic glass between 10mK and 300K. In order to measure the entire temperature range, in particular the low temperature part, new experimental techniques were developed. Using an inductive readout scheme for a double paddle oscillator it was possible to determine the internal friction and the relative change of sound velocity of bulk metallic glasses with high precision. This allowed for a detailed comparison of the data with different models. The analysis focuses on the low temperature regime where the properties of glassy materials are governed by atomic tunneling systems as described by the tunneling model. The influence of conduction electrons in the normal conducting state and quasiparticles in the superconducting
state of the glass were accounted for in the theoretical description, resulting in a good agreement over a large temperature range between measured data and prediction of the tunneling model.
