Phonon softening ofNb3Sn in[ζζζ]Tmodes

Neutron scattering measurements have been extended to the [$\zeta \zeta \zeta$] transverse branch of ${\mathrm{Nb}}_3$Sn. In contrast to the prediction of Gor'kov, this branch also shows a pronounced phonon softening. We conclude that all phonon branches in ${\mathrm{Nb}}_3$Sn exhibit softening for a wide range of $q$ towards the martensitic transition at 45 K.