Statistical analysis of emission, interaction and annihilation of phonons by kink motion in ferroelastic materials

Our early work showed that the evolution of the twin boundary pattern exhibits an avalanche behavior upon external loading of ferroelastic materials [Salje et al., Phys. Rev. B 83, 104109 (2011)]. The distribution of "jerks" (singularities of potential energy change) was found to follow a power law distribution below a Vogel-Fulcher temperature, mainly related to the movement of kinks in domain boundaries. We use molecular dynamics simulations to study the nucleation, scattering, and annihilation of phonons that are generated by the nucleation and propagation of such kinks. The interaction and scattering of phonons are correlated over a short time period and gradually become uncorrelated before annihilation at large temperature intervals. The movement and interaction of phonons show avalanche behavior. The probability of finding energy jerks follows a power law with exponents around 2.5-3. The distribution of waiting times between jerks also follows a power law. At temperatures above the Vogel-Fulcher temperature, scattering with thermal phonons becomes predominant and no phononic avalanches were observed.