[22p-C102-1~16] 22.1 Joint Session M "Phonon Engineering"

▼ [22p-C102-5] Transition from ballistic to hydrodynamic phonon transport regime in submicroscale purified graphite ribbons

〇(D)Huang Xin¹, Yangyu Guo¹, Yunhui Wu¹, Satoru Masubuchi¹, Kenji Watanabe², Takashi Taniguchi^1,2, Zhongwei Zhang¹, Sebastian Volz^1,3, Tomoki Machida¹, Masahiro Nomura¹ (1.Univ. of Tokyo, 2.NIMS, 3.LIMMS)

Keywords:phonon hydrodynamics, phonon Poiseuille flow, graphite ribbon

In this work, we experimentally investigate phonon Poiseuille flow in isotopically-enriched submicroscale graphite ribbons from 10 to 200 K. We first revisit the occurrence criterion of phonon Poiseuille flow and demonstrate a more rigorous criterion, i.e., a rise of the ratio thermal conductivity to the ballistic thermal conductance with temperature increases. Based on this explicit criterion, we observe no hydrodynamic flow in 500 nm and 1 um-wide ribbons, weak hydrodynamic flow in a 3 μm-wide ribbon, and prominent phonon Poiseuille flow in a wider ribbon of 5 μm width. A clear transition from ballistic to hydrodynamic regimes with the widening of the ribbon is thus observed. This work orientates future progress for a deeper understanding of phonon hydrodynamics in solids.