講演情報
[15p-W9_323-9]Two-stage graphite Tesla valve thermal diode based on phonon hydrodynamics
〇Huang Xin1, Kenji Watanabe2, Takashi Taniguchi1,2, Masahiro Nomura1 (1.IIS, Univ. of Tokyo, 2.NIMS)
キーワード：
Thermal diode、Phonon hydrodyanmics、Tesla valve
Thermal diodes, which regulate heat flow through temperature bias, hold promise for energy-efficient applications in AI and sustainable technology. Despite their potential, industrial progress has been limited mainly to incremental efficiency gains.Inspired by the Tesla valve from fluid dynamics, we previously demonstrated a thermal rectification ratio of 1.152 in a single-stage graphite structure. Here, we extend this approach by designing a two-stage Tesla valve on an isotopically enriched graphite flake (99.93% ¹²C) to suppress phonon-isotope scattering. The valve, fabricated on a 150 nm-thick flake with 4.5 µm wide channels, allows bidirectional heat flow comparison under opposite temperature biases.Using thermoreflectance measurements, we tracked heat decay in forward (τ_F) and backward (τ_B) directions. The diodicity (τ_B/τ_F) increased with temperature from 20 K, peaking at 1.23 at 50 K—a measurable improvement over the single-stage design. This enhancement is attributed to phonon hydrodynamics: at higher temperatures, momentum-conserving normal scattering dominates, enabling phonon fluid-like flow in the forward direction, while the Tesla valve geometry induces backflows that resist reverse heat transfer.This work demonstrates that engineered phonon hydrodynamic channels can effectively amplify thermal rectification, offering a viable pathway toward high-performance, scalable thermal diodes.