发表机构
Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology; Laboratoire de Physique et d’Étude de Matériaux (CNRS) ESPCI Paris, PSL Research University（华中科技大学物理学院和武汉国家高能磁场中心; 巴黎高等物理化工大学国立科学研究中心物质物理与研究实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文通过对TaAs₂晶体的输运测量，发现5-15K区间存在电子-声子双流体，观测到声子泊肃叶流动及电子流体动力学特征，为半金属电子-声子耦合流体动力学研究提供了实验依据。
AI 中文摘要
当准粒子间的动量守恒碰撞变得显著时，扩散输运会出现流体动力学修正，且这种修正已在电子和声子体系中被观测到。一个新兴前沿领域是耦合电子-声子（e-ph）流体动力学。本文通过对不同杂质浓度的TaAs₂晶体开展电输运和热输运测量，发现在5至15K的温度区间内出现了电子-声子双流体。在该温度范围内，晶格热导率呈现出快于T³的温度依赖关系，这源于非单调且与纯度相关的声子平均自由程，是声子泊肃叶流动的特征。然而，强电子-声子耦合阻碍了弹道区的出现，晶格热导率中的量子振荡观测结果证实了这一点。显著的声子介导电子动量交换加剧了维德曼-弗兰兹定律的偏离，使量子寿命与输运寿命相差两个数量级，这是半金属中电子流体动力学的特征。研究结果表明，在电子-声子耦合优化的半金属中，由于低温声子波长与费米波长匹配，电子与声子库之间的动量和能量流动频率与库内部的流动频率相当。
英文摘要
Hydrodynamic corrections to diffusive transport can arise when momentum-conserving collisions between quasiparticles become prominent, and they have been documented for both electrons and phonons. An emerging frontier topic is coupled electron-phonon (e-ph) hydrodynamics. Here, through electrical and thermal transport measurements on TaAs2 crystals with different impurity levels, we document the emergence of an e-ph bifluid in the temperature window of 5 to 15 K. Within this range, the lattice thermal conductivity exhibits a faster-than-T^3 temperature dependence, as a consequence of non-monotonic and purity-dependent phonon mean free paths, a signature of phonon Poiseuille flow. However, strong e-ph coupling impedes the emergence of a ballistic regime. This is corroborated by the observation of quantum oscillations in the lattice thermal conductivity. Prominent phonon-mediated momentum exchange between electrons amplifies the violation of the Wiedemann-Franz law and yields a two-order-of-magnitude discrepancy between quantum and transport lifetimes, a signature of electron hydrodynamics in semimetals. Our results imply that in semimetals with optimized e-ph coupling, thanks to matching between the cryogenic phonon wave?length and the Fermi wavelength, momentum and energy flow between the electron and phonon reservoirs as frequently as within each reservoir.
Comments7 pages, 4 figures
