Interaction of phonons with discrete breather in strained graphene

TL;DR

This study numerically investigates how small-amplitude phonons interact with discrete breathers in strained graphene, revealing frequency-dependent transparency and reflection behaviors that influence energy transport.

Contribution

It introduces a quasi-one-dimensional model of strained graphene to analyze phonon-breather interactions and identifies frequency-dependent transmission and reflection phenomena.

Findings

Low-frequency phonons (<6 THz) pass through breathers without radiation.

High-frequency phonons are mainly reflected or transmitted, with energy radiation from breathers.

Energy density sum exceeds incident energy, indicating energy exchange during interaction.

Abstract

We numerically analyze the interaction of small-amplitude phonon waves with standing gap discrete breather (DB) in strained graphene. To make the system support gap DB, strain is applied to create a gap in the phonon spectrum. We only focus on the in-plane phonons and DB, so the issue is investigated under a quasi-one-dimensional setup. It is found that, for the longitudinal sound waves having frequencies below 6 THz, DB is transparent and thus no radiation of energy from DB takes place; whereas for those sound waves with higher frequencies within the acoustic (optical) phonon band, phonon is mainly transmitted (reflected) by DB, and concomitantly, DB radiates its energy when interacting with phonons. The latter case is supported by the fact that, the sum of the transmitted and reflected phonon energy densities is noticeably higher than that of the incident wave. Our results here may provide insight into energy transport in graphene when the spatially localized nonlinear vibration modes are presented.