Correspondence: Reply to ‘Phantom phonon localization in relaxors’

Abstract

The Correspondence by Gehring et al. [1] mistakes Anderson phonon localization for the concept of an atomic-scale local mode. An atomic-scale local mode refers to a single atom vibrating on its own within a crystal. Such a local mode will have an almost flat intensity profile, but this is not the same as phonon localization. Anderson localization is a wave interference effect in a disordered system that results in waves becoming spatially localized [2]. The length scale of the localized waves is set by the wavelength [2], which is approximately 2 nm in this case. This larger length scale in real space means narrower intensity profiles in reciprocal space. We conclude that the claims in the Correspondence by Gehring et al. [1] are incorrect because they mistakenly assume that the length scale for Anderson localization is atomic, and because the experimental observations rule out multiple scattering as the origin.