Dynamic Properties, Low-Lying Excitations

According to the decrease of T0, with composition we expect low-lying nonelectronic excitations in the specific heat especially close to Z = 1.8 e/a due to the thermal excitation of phonon-rotons. In Sect. 5.5.3.b, we already mentioned that those excitations indeed have been observed for Au-Sn. ydis-values extracted from specific-heat measurements well below T c are shown in Fig. 5.28 for (Au, Cu)-Sn, clearly showing the increasing contribution of phonon-rotons at this value. The strong increase of the linear specific heat for Cu-Sn close to Z 

The stability of the metallic glasses under consideration with decreasing Sn-content seems to be influenced by the decrease of T0 or a 0, respectively. If ca0 becomes very low for alloys with Z approaching 1.8 e/a, indicated by the increase of the ydis-contribution, the system finally crystallizes. Phonon-roton 

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