Dynamical structure factor and frequency distribution of the metallic glass Cu₄₆Zr₅₄ at room temperature

The dynamical structure factor of glassy Cu₄₆Zr₅₄ has been measured at room temperature, for momentum transfers between 1 and 8 AA^-1 and energies (h(cross) omega =E₀-E) between -45 and 45 meV, using neutron inelastic scattering. From the measured time-of-flight spectra a generalised frequency distribution has been determined. The experiment was repeated after crystallisation of the sample. The results show a strong increase of low-frequency modes in the amorphous sample compared with the polycrystal, and the frequency distribution of the metallic glass shows a slope approximately omega ^4/3 between 4.7 and 7 meV, where the frequency distribution of the polycrystalline sample still shows a Debye type of spectrum.