[24p-F407-1~17] 22.1 Joint Session M "Phonon Engineering"

▼ [24p-F407-3] Investigation of phonon Poiseuille flow in purified graphite crystals

〇(DC)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, isotopically purified graphite

In this work, we experimentally investigate phonon Poiseuille flow in suspended graphite ribbons with both natural and purified carbon isotope concentrations. Based on a steady-state micro-TDTR setup, we first study the suppression of thermal conductivity by isotope-phonon scattering in a natural graphite ribbon at the intermediate temperature range. Furthermore, we examine the observation of phonon Poiseuille flow under an explicit criterion. As the temperature increases, thermal conductivity is enhanced over the ballistic case from 30 to 60 K, attributed to the hydrodynamic transport of phonons in the isotopically purified sample. Whereas the value of thermal conductivity over ballistic limit solely decreases in the natural graphite sample, which indicates the absence of phonon Poiseuille flow resulted from the sufficient momentum-destroyed isotope scattering. Supported by our theoretical calculation by solving the phonon Boltzmann transport equation (BTE), we demonstrate that the phonon Poiseuille flow can only be observed in isotopically purified graphite ribbon. This result thus orientates future progress for a deeper understanding of phonon hydrodynamics in solids.