It has been found that in disordered one-dimensional (1D) and 2D media, all finite frequency phonons are localized, while in 3D, mobility edges separating low-frequency extended states and high-frequency localized states exist (24, 30).

What is phonon localization?

Localization is characterized by a phonon frequency–dependent localization length, ξ. Phonon transmission decays exponentially for localized modes as e^−L/ξ, where L is the total thickness of the SL.

What causes phonon?

phonon, in condensed-matter physics, a unit of vibrational energy that arises from oscillating atoms within a crystal. ... Whereas electrons are responsible for the electrical properties of materials, phonons determine such things as the speed of sound within a material and how much heat it takes to change its temperature.