Observation of superdiffusive phonon transport in aligned atomic chains
Observation of superdiffusive phonon transport in aligned atomic chains
复制标题
DOI：
10.1038/s41565-021-00884-6
复制
发表时间：
2021-04-15
影响因子：
38.3
通讯作者：
Li, Deyu
中科院分区：
文献类型：
--
作者：
Yang, Lin;Tao, Yi;Li, Deyu
当电荷和/或能量载流子被限制在一维（1-4）中时，可以发生快速现象。其中一个例子是一维晶格的发散热导率（kappa），即使在存在非谐原子间相互作用的情况下也是如此-这是1955年提出的费米-帕斯塔-乌拉姆-钦古悖论的直接结果（5）。kappa的这种长度依赖性，也称为超扩散声子输运，是一个经典的持续关注的异常现象（6-9）。到目前为止，这个概念仍然是纯理论的，因为足够长的孤立的单原子链在实验上是无法实现的。在这里，我们报告的观察依赖于长度的κ延伸超过42.5 μ m，在室温下的货车德瓦尔斯晶体NbSe 3纳米线。我们发现，Kappa遵循1/3幂律与线长，这提供了指向超扩散声子输运的实验证据。相反，由于声子边界散射的经典尺寸效应，所观察到的卡帕显示了25倍的增强，作为纳米线的特征尺寸从26纳米降低到6.8纳米，同时显示正常的超扩散过渡。我们的分析表明，这些有趣的观察源于运输的一维声子激发的结果，弹性硬化与五倍增强的杨氏模量。所观察到的热导率随样品长度的持续发散趋势揭示了创造新型货车范德华晶体基热超导体的真实的可能性，其kappa值高于任何已知材料。
Fascinating phenomena can occur as charge and/or energy carriers are confined in one dimension(1-4). One such example is the divergent thermal conductivity (kappa) of one-dimensional lattices, even in the presence of anharmonic interatomic interactions-a direct consequence of the Fermi-Pasta-Ulam-Tsingou paradox proposed in 1955(5). This length dependence of kappa, also known as superdiffusive phonon transport, presents a classical anomaly of continued interest(6-9). So far the concept has remained purely theoretical, because isolated single atomic chains of sufficient length have been experimentally unattainable. Here we report on the observation of a length-dependent kappa extending over 42.5 mu m at room temperature for ultrathin van der Waals crystal NbSe3 nanowires. We found that kappa follows a 1/3 power law with wire length, which provides experimental evidence pointing towards superdiffusive phonon transport. Contrary to the classical size effect due to phonon-boundary scattering, the observed kappa shows a 25-fold enhancement as the characteristic size of the nanowires decreases from 26 to 6.8 nm while displaying a normal-superdiffusive transition. Our analysis indicates that these intriguing observations stem from the transport of one-dimensional phonons excited as a result of elastic stiffening with a fivefold enhancement of Young's modulus. The persistent divergent trend of the observed thermal conductivity with sample length reveals a real possibility of creating novel van der Waals crystal-based thermal superconductors with kappa values higher than those of any known materials.