Anharmonic Enhancement of Interfacial Phonon-Phonon Coupling in Twisted TMD Bilayers

The rich quantum landscape of van-der-Waals (vdW) stacked materials holds promise for next-generation nanodevices, yet the challenge of heat management due to weak interlayer thermal conductivity hinders potential applications. Here, we computationally address the question of whether the anharmonicity in layered materials can be tuned as a potential degree of freedom to engineer interlayer phonon coupling in such structures. Specifically, we investigate two primary mechanisms: (1) interlayer twisting, where varying twist angles substantially influence the phonon anharmonicity through localized moiré-patterned domains; and (2) the tuning of phonon dispersion with carrier doping, wherein the inherent phonon anharmonicity is tuned by accompanying changes in the electronic structure. Our work approach employs first-principles calculations and compressive sensing techniques to efficiently estimate interatomic forces in large, incommensurate structures that are typically prohibitive in standard DFT calculation. Our results offer insights into the complex interplay between twist angles, phase boundaries, and thermal properties of transition metal dichalcogenide (TMDs) as novel ways to address heat management in layered materials.