Coherent phonon transport and Anderson localization in WS₂/MoS₂ superlattices

Understanding the interplay between coherent and incoherent phonon transport is essential for designing efficient nanoscale devices. Although many studies focus on three-dimensional materials, we still lack a systematic understanding of wave-based transport and localization effects in two-dimensional systems. Here we show that perfectly periodic heterostructures made of alternating layers of tungsten disulfide and molybdenum disulfide exhibit a non-monotonic pattern in their thermal conductance profile, a direct signature of coherent transport. In contrast, introducing aperiodicity leads to the emergence of Anderson localization, visible as an exponential decay of phonon transmission with superlattice length. Using first-principles combined with atomistic Green-function calculations, we quantify how structural disorder suppresses in-plane thermal conductance through coherent localization rather than incoherent scattering. These findings clarify how distinct coherent transport regimes arise in ordered versus aperiodic two-dimensional superlattices, and establish principles for controlling heat flow through wave interference in layered materials.