momentum transfer. In the cubic phase at $T = 80$ K (red points), $\Gamma_p$ attains a maximum halfway from the $\Gamma$ to the $\textrm{K}$ point.](lw_80_10_Gamma){width="1\columnwidth"}

The temperature dependence of the TA2 phonons at $q = (\overline{\frac{1}{2}} \frac{1}{2} 0)$ and $q = (\overline{0.4}\ 0.4\ 0)$ are shown in Fig. \[fig:linewidths\_T\]. $\Gamma_p$ increases when warming the sample from $T = 10\,\mathrm{K}$ towards the Néel-transition at $T_{N} \approx 40\,\mathrm{K}$. Here $\Gamma_p$ seems to saturate at $\approx 200\, \mathrm{\upmu eV}$ before increasing again to a maximum value $\Gamma_p \approx 450\, \mathrm{\upmu eV}$ in the vicinity of the structural phase transition $T_{OO} \approx 63\,\mathrm{K}$.

![\[fig:linewidths\_T\] Temperature dependence of the TA2 phonons at $Q = (3.5\ 4.5\ 0)$ using conventional TAS-spectroscopy (red dots) and $Q = (3.6\ 4.4\ 0)$ using TRISP (blue triangles). A subtle plateau can be identified between $T_N$ and $T_{OO}$. $\Gamma_p$ increases to approximately 0.45 meV in the cubic phase where it remains constant up to $T = 200$ K.](lw_3_5_Gamma){width="1\columnwidth"}

Note that the linewidth at $q = (\overline{0.4}\ 0.4\ 0)$ was determined with high accuracy by means of the neutron-resonance spin-echo (NRSE) technique at the triple axis spectrometer TRISP at MLZ [@TRISP]. TRISP was set up in a negative-negative-positive scattering configuration. The NRSE 