Phonon Magic Angle in Two-Dimensional Puckered Homostructures

TL;DR

This paper introduces the concept of a 'phonon magic angle' in 2D puckered materials, revealing how twisting layers can enhance or regulate phonon transport, with implications for electronic and photonic device engineering.

Contribution

The study extends twistnonics to phonon engineering in 2D puckered materials, discovering a phonon magic angle that can enhance phonon transport via van der Waals confinement.

Findings

Phonon magic angle enhances phonon transport.

Twisting regulates thermal transport properties.

Suppression of acoustic phonons reduces phonon lifetimes.

Abstract

The emergence of twistronics provides an unprecedented platform to modulate the band structure, resulting in exotic electronic phenomena ranging from ferromagnetism to superconductivity. However, such concept on phonon engineering is still lacking. Here, we extend the 'twistnonics' to 2D puckered materials with a 'phonon magic angle' discovered by molecular dynamics simulation. The phonon magic angle, with the TP-1 and TP-2 direction overlapped, remains a high level or even enhances phonon transport capability due to van der Waals confinement. This novel phenomenon originates from the confined vdW interaction and ordered atomic vibration caused by the perfect lattice arrangement that the atoms of the top layer can be stuck to the spaces of the bottom layer. Moreover, it is found that both the in-plane and out-of-plane thermal transport properties can be effectively regulated by applying the twist. Through the phononic and electronic analysis, the deterioration of phonon transport capability for other twist angles are attributed to the suppression of acoustic phonon modes, reduction of phonon lifetimes and mismatched lattice vibration between layers. Our findings shed light on the twistnonics of low-dimensional asymmetrical materials and can be further extended to electronic and photonic devices.