# Valley filtering effect of phonons in graphene with a grain boundary

## TL;DR

This paper demonstrates that phonons in graphene can be selectively filtered by valley using grain boundaries, opening new avenues for phonon control and valley phononics in material science.

## Contribution

It introduces the concept of valley filtering for phonons in graphene, a novel idea extending valleytronics to phononic systems.

## Key findings

- Perfect valley filtering observed at specific energies for flexural phonon modes.
- Valley filtering effectiveness is linked to phonon valley pocket anisotropy.
- Fano-like resonance can enhance valley filtering performance.

## Abstract

Due to their possibility to encode information and realize low-energy-consumption quantum devices, control and manipulation of the valley degree of freedom have been widely studied in electronic systems. In contrast, the phononic counterpart--valley phononics--has been largely unexplored, despite the importance in both fundamental science and practical applications. In this work, we demonstrate that the control of "valleys" is also applicable for phonons in graphene by using a grain boundary. In particular, perfect valley filtering effect is observed at certain energy windows for flexural modes and found to be closely related to the anisotropy of phonon valley pockets. Moreover, valley filtering may be further improved using Fano-like resonance. Our findings reveal the possibility of valley phononics, paving the road towards purposeful phonon engineering and future valley phononics.