论文标题
在室温下观察到狄拉克流体的巨型和可调的热扩散率
Observation of giant and tuneable thermal diffusivity of Dirac fluid at room temperature
论文作者
论文摘要
传导材料通常表现出扩散或弹道电荷传输。但是，当电子电子相互作用占主导地位时，出现了具有粘性电荷流量的流体动力学状态（1-13）。更严格的条件最终产生了量子关键的迪拉克流体状态，在该方案中，电子热可以比电荷更有效地流动（14-22）。在这里，我们在扩散和流体动力学方面观察石墨烯中的热传输，并在室温下，使用载体温度和载体密度作为控制旋钮报告在室温下向做奶油流体机制的可控过渡。我们介绍了使用飞秒时间和纳米空间分辨率的时空热电显微镜的技术，该技术允许跟踪电子热传播。在扩散制度中，我们发现$ \ sim $ 2,000 cm $^2 $/s的热扩散率与充电运输一致。值得注意的是，在动量放松之前的流体动力学时间窗口中，我们观察到热量扩散，对应于高达70,000 cm $^2 $/vs的巨大扩散率，这表明狄拉克流体。这些结果对于纳米级热管理等应用是有希望的。
Conducting materials typically exhibit either diffusive or ballistic charge transport. However, when electron-electron interactions dominate, a hydrodynamic regime with viscous charge flow emerges (1-13). More stringent conditions eventually yield a quantum-critical Dirac-fluid regime, where electronic heat can flow more efficiently than charge (14-22). Here we observe heat transport in graphene in the diffusive and hydrodynamic regimes, and report a controllable transition to the Dirac-fluid regime at room temperature, using carrier temperature and carrier density as control knobs. We introduce the technique of spatiotemporal thermoelectric microscopy with femtosecond temporal and nanometre spatial resolution, which allows for tracking electronic heat spreading. In the diffusive regime, we find a thermal diffusivity of $\sim$2,000 cm$^2$/s, consistent with charge transport. Remarkably, during the hydrodynamic time window before momentum relaxation, we observe heat spreading corresponding to a giant diffusivity up to 70,000 cm$^2$/Vs, indicative of a Dirac fluid. These results are promising for applications such as nanoscale thermal management.
