Figure 1

IXS spectra of ${\mathrm{Ni}}_{33}{\mathrm{Zr}}_{67}$ at the indicated fixed $Q$ values (open dots). Also reported are the best-fit line shapes (continuous lines; see text). The low energy structures at $E\approx 8\mathrm{meV}$ observed around $Q\approx 11{\mathrm{nm}}^{-1}$ are spurious scattering from the kapton windows of the sample container.Reuse & Permissions

Figure 2

Dispersion curve $\hslash \Omega (Q)$ of the NiZr alloy as obtained from the IXS and INS experiments. The momentum transfers have been scaled to $Q_p$ to account for the different structural properties due to the different compositions ($Q_p^{({\mathrm{Ni}}_{33}{\mathrm{Zr}}_{67})}=25.7{\mathrm{nm}}^{-1}$ and $Q_p^{({\mathrm{Ni}}_{67}{\mathrm{Zr}}_{33})}=29{\mathrm{nm}}^{-1}$). Inset: $Q$ dependence of the sound velocity $v=\Omega /Q$ as measured by IXS.Reuse & Permissions

Figure 3

(a) $Q$ dependency of the damping of the observed excitation (full triangles). A transition from the $Q^2$ to a linear dependence of the damping around $Q=7{\mathrm{nm}}^{-1}$ can be observed. Values of $\Omega /\pi$ are also reported to identify the Ioffe-Regel crossover (full circles), together with the boson peak energy. Open triangles show the sound attenuation calculated by means of molecular dynamics in a simple metal, which shows a qualitatively similar behavior [14]. (b) Energy dependence of the damping: the breakdown of the quadratic dependence is shifted to higher energies but not completely removed. (c) reduced vibrational density of states $g(\omega )/{\omega }^2$ for ${\mathrm{Ni}}_{33}{\mathrm{Zr}}_{67}$ as measured by INS [20] and calculated by molecular-dynamic simulations [6].Reuse & Permissions

Figure 4

$Q$ dependence of the elastic/total scattered intensity ratio. Inset: static structure factor; note the prepeak at $Q\approx 14{\mathrm{nm}}^{-1}$), where $A(Q)$ changes its slope.Reuse & Permissions