Graphite Thermal Tesla Valve

As electronic devices become increasingly compact and powerful, efficient thermal management is crucial for performance, longevity, and safety. This study demonstrates a novel approach to thermal rectification by extending the concept of the Tesla valve, originally designed for fluid flow, to solid-state heat conduction in graphite materials.
We utilized isotopically enriched graphite with ¹³C content reduced from 1.1% to 0.02% to create a solid-state Tesla valve structure. This material exhibits phonon hydrodynamic behavior, allowing for the formation of phonon Poiseuille flow [1]. We observed thermal rectification effects of up to 15% in the temperature range of 25-60 K. The graphite Tesla valve was fabricated as an air-bridge structure with a thickness of 90 nm and a width of 4.5 μm to ensure heat flow exclusively within the graphite. Thermal conductivity measurements were performed on forward and reverse configurations at various temperatures.
Our results demonstrate that the thermal rectification effect is most pronounced at around 45 K, where the thermal conductivity in the forward direction is 15.4% higher than in the reverse direction. This effect was observed only within the temperature range where phonons exhibit fluid-like properties [2]. This research represents a significant step towards realizing solid-state thermal rectification devices by leveraging the hydrodynamic behavior of phonons in graphite. The development of such thermal management technologies could lead to substantial advancements in the performance and efficiency of various electronic devices.
Reference:
[1] X. Huang, …, and M. Nomura, “Observation of phonon Poiseuille flow in isotopically purified graphite ribbons”, Nat. Commun. 14, 2044 (2023).
[2] X. Huang, …, and M. Nomura, “A graphite thermal Tesla valve driven by hydrodynamic phonon transport,” Nature 634, 1086 (2024).