Stacking-Engineered Thermal Transport and Phonon Filtering in Rhenium Disulfide

TL;DR

This study shows how stacking order in multilayer ReS2 can be used to control cross-plane heat transport, revealing long phonon mean free paths and phonon filtering effects that enable tuning heat conduction regimes.

Contribution

It demonstrates the impact of stacking order on phonon transport and introduces a neural network-based method to analyze phonon filtering in ReS2.

Findings

AA stacking doubles cross-plane thermal conductivity compared to AB stacking

Phonon mean free paths are remarkably long (>= 200-300 nm)

Phonon filtering is frequency-selective and influenced by interlayer coupling

Abstract

Cross-plane heat transport is a critical bottleneck for van der Waals (vdW) electronics, yet its microscopic governing principles remain elusive. We demonstrate that stacking order is an effective control knob for cross-plane phonon transport in multilayer Rhenium Disulfide (ReS2). Thickness-dependent thermal conductivity measurements reveal remarkably long cross-plane phonon mean free paths (MFPs) (>= 200-300 nm) and provide a direct experimental observation of the transition from quasi-ballistic transport to a thickness-independent ballistic limit. AA stacking exhibits nearly double the cross-plane thermal conductivity of AB stacking, driven by longer acoustic phonon lifetimes from a more "coherent" interlayer registry. Integrated deep neural-network molecular dynamics reveals that phonon filtering in ReS2 is fundamentally frequency-selective: weak vdW coupling acts as a low-pass filter, whereas stronger coupling broadens the transmission passband. These results establish ReS2 as a model system where stacking order and interlayer coupling can be engineered to tune heat conduction across diffusive, quasi-ballistic, and ballistic regimes, offering a new framework for thermal management in 2D electronics.