Understanding nanoscale thermal transport is critical for nano-engineered devices such as quantum sensors, thermoelectrics, and nanoelectronics. However, despite overwhelming experimental evidence for nondiffusive heat dissipation from nanoscale heat sources, the underlying mechanisms are still not understood. In this work, we show that for nanoscale heat source spacings that are below the mean free path of the dominant phonons in a substrate, close packing of the heat sources increases in-plane scattering and enhances cross-plane thermal conduction. This leads to directional channeling of thermal transport—a novel phenomenon. By using advanced atomic-level simulations to accurately access the lattice temperature and the phonon scattering and transport properties, we finally explain the counterintuitive experimental observations of enhanced cooling for close-packed heat sources. This represents a distinct fundamental behavior in materials science with far-reaching implications for electronics and future quantum devices.

了解纳米级热传输对于量子传感器、热电和纳米电子学等纳米工程设备至关重要。然而，尽管有压倒性的实验证据表明纳米级热源的非扩散散热，但其潜在机制仍不清楚。在这项工作中，我们表明，对于低于基板中主要声子的平均自由程的纳米级热源间距，热源的紧密堆积会增加面内散射并增强跨面热传导。这导致了热传输的定向通道——一种新现象。通过使用先进的原子级模拟来准确获取晶格温度和声子散射和传输特性，我们最后解释了对密排热源增强冷却的违反直觉的实验观察。这代表了材料科学中一种独特的基本行为，对电子产品和未来的量子设备具有深远的影响。