Figure 8.

Real (red dashed line) and imaginary (blue solid line) parts of dielectric function in NiH${}_{0.25}$ calculated at q = 0.027 Å${}^{-1}$ pointing in [100] symmetry direction and respective loss function, −Im$\left[{ϵ}^{-1}\right]$, (black solid line). Three peaks in Im$\left[ϵ\right]$ generated by the states marked in the DOS of Figure 7b,c are labeled by respective symbols. The energy regions where Re$\left[ϵ\right]$ crosses the zero line with positive slope are marked by arrows. In the loss function a peak corresponding to a long-lived spin acoustic plasmon is marked as SAP${}_2$. A weaker acoustic plasmon peak is denoted as SAP${}_1$.