Atomistic study of heat transfer between 3C-SiC slabs in the extreme near-field regime

HF Yang and Z Gong and WB Zhang and CY Zhao, PHYSICAL REVIEW B, 112, 115438 (2025).

DOI: 10.1103/2nj4-9rlv

Understanding heat transfer at extreme near-field scales is crucial for advancing thermal management at nanoscale and subnanoscale levels, where traditional continuum theories often fail. However, existing studies have mainly focused on larger gap sizes (>10 & Aring;), and the transition between radiative and conductive mechanisms in the extreme near-field remains underexplored. To fill this gap, we use nonequilibrium molecular dynamics (NEMD) simulations to investigate heat transfer between two plates with vacuum gaps ranging from 0.5 to 7 & Aring;. The choice of 3C-SiC is motivated by its well-defined dielectric properties and relevance in nanotechnology. By using dielectric responses derived from equilibrium molecular dynamics simulations, we compare both local and nonlocal near-field radiative heat transfer with NEMD results and reveal significant deviations from continuum theory in the extreme near-field regime. Subsequently, we analyze the scaling behavior of thermal conductance with gap distance, identifying a power- law decay of d(-1.48) for gaps smaller than 3.8 & Aring; and d(-5.37) for larger gaps, influenced by the interplay of the Vashishta potential, atomic interaction strength related to the lattice constant, and the system's tendency to minimize potential energy through gap relaxation. Moreover, due to lattice anharmonicity, energy transmission across the nanogap increases with rising temperature, as demonstrated by further simulations. These results provide insights into energy transfer mechanisms in the extreme near field and suggest directions for future research.

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