As electronic devices become increasingly compact and powerful, efficient thermal
management is crucial for performance, reliability, and safety. This study explores 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.
Developing such thermal management technologies could lead to substantial advancements in
the performance and efficiency of various electronic devices.