Impact of dimensional crossover on phonon transport in van der Waals materials: a case study of graphite and graphene

Abstract

Using first-principles modeling, we investigate how phonon transport evolves in layered/van der Waals materials when going from 3D to 2D, or vice versa, by gradually pulling apart the atomic layers in graphite to form graphene. Focus is placed on identifying the features impacting thermal conductivity that are likely shared with other layered materials. The thermal conductivity $\kappa$ of graphite is found to be lower than that of graphene mainly due to changes in the phonon dispersion driven by van der Waals coupling. Specifically, as the atomic layers are brought closer together, the acoustic flexural phonons in graphene form low-energy optical flexural phonons in graphite that possess lower in-plane velocities, density-of-states and phonon occupation, thus reducing $\kappa$. Similar dispersion changes, and impact on thermal conductivity, can be expected in other van der Waals materials when transitioning from 2D to 3D. Our findings also indicate that the selection rules in graphene, which reduce phonon-phonon scattering and contribute to its large $\kappa$, effectively hold as the atomic layers are brought together to form graphite. While the selection rules do not strictly apply to graphite, in practice similar scattering behavior is displayed due in part to the weak inter-layer coupling. This suggests that van der Waals materials, in bulk 3D form, may have lower phonon-phonon scattering rates than other non-layered bulk materials.

14 pages, 10 figures

References in corpus (8)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Advanced capabilities for materials modelling with Quantum ESPRESSO
• The phonon dispersion of graphite by inelastic x-ray scattering
• Observation of second sound in graphite at temperatures above 100 K
• A revisit to phonon-phonon scattering in single-layer graphene
• Crossover of ballistic, hydrodynamic, and diffusive phonon transport in suspended graphene
• Phonon Confinement and Transport in Ultrathin Films
• Mapping Phonon Modes from Reduced-Dimensional to Bulk Systems

Cited by in corpus (1)

• First-principles analysis of intravalley and intervalley electron-phonon scattering in thermoelectric materials