Giant Manipulation of Phonon Hydrodynamics in Ferroelectric Bilayer Boron Nitride at Room Temperature and Beyond
Giant Manipulation of Phonon Hydrodynamics in Ferroelectric Bilayer Boron Nitride at Room Temperature and Beyond
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DOI：
10.1021/acsaem.2c01274
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发表时间：
2022-07
影响因子：
6.4
通讯作者：
Zhonghua Yang;Kunpeng Yuan;Nan Li;Xiaoliang Zhang;Ming Hu
中科院分区：
文献类型：
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作者：
Zhonghua Yang;Kunpeng Yuan;Nan Li;Xiaoliang Zhang;Ming Hu
声子流体力学是一种有趣的热输运机制，它为声子操纵和热管理提供了很好的机会。几十年来，人们一直认为声子流体动力学只在很低的温度下发生，直到最近，才证实声子在室温下可以有效地在低维材料中流动。然而，到目前为止，还没有关于通过外加电场等可逆方法在室温下操纵声子流体动力学的研究报道。受铁电双层氮化硼(BN)自发面外极化的激励，研究了面内电场对声子输运的影响。当电场轻微开启时，双层BN的晶格热导率急剧增加，最大增强因子为∼2，峰值热导率达到840W/mK。如此巨大的变化源于占主导地位的声子流体动力学。通过调节外加电场，即使在室温下，声子流体动力学也可以贡献双层BN中总热输运的50%，这表明声子流体动力学的操纵能力很强。在很宽的频率范围内(<；10THz)，正常的(N)声子输运比阻性UmkLapp过程强2个数量级。通过对模能级声子行为的分析，我们发现这种增强主要是由两个低频声子分支(面外ZA和低位ZO1)贡献的。在面内电场作用下，氮原子周围的电荷数目和电荷分布都会发生很大的变化，这是铁电材料自发电极化的自然响应，导致声子重整化和声子非谐性的调制。我们的研究为在不改变原子结构的情况下动态控制层状铁电材料中的声子流体动力学奠定了基础，并将对新兴的应用产生重大影响。
Phonon hydrodynamics is an intriguing thermal transport mechanism that offers a great opportunity for phonon manipulation and thermal management. For decades, it has been believed that phonon hydrodynamics occurs only at very low temperatures, until very recently, it was confirmed that phonons can efficiently flow in low-dimensional materials at room temperature. However, to date, no study has been reported on the manipulation of phonon hydrodynamics at room temperature via reversible methods such as an external electric field. Motivated by the spontaneous out-of-plane polarization of ferroelectric bilayer boron nitride (BN), we investigate the effect of in-plane electric fields on phonon transport. With the electric field slightly switched on, the lattice thermal conductivity of bilayer BN steeply increases with a maximum augmentation factor of ∼2, and the peak thermal conductivity reaches 840 W/mK. Such a colossal change stems from the dominant phonon hydrodynamics. By tuning the external electric field, the phonon hydrodynamics can be manipulated to contribute 50% of the overall thermal transport in bilayer BN even at room temperature, indicating robust manipulation of phonon hydrodynamics. Over a broad frequency range (<10 THz), the Normal (N) phonon transport is 2 orders of magnitude stronger than that of the resistive Umklapp process. By analyzing mode level phonon behavior, we reveal that such enhancement is mainly contributed by the two low-frequency phonon branches (out-of-plane ZA and low-lying ZO1). Under the in-plane electric field, both the number of charges and charge distribution around the nitrogen atom can be largely altered, which is the natural response of the spontaneous electric polarization as a ferroelectric material, leading to phonon renormalization and modulation of phonon anharmonicity. Our study paves the way for dynamically controlling phonon hydrodynamics in layered ferroelectrics at room temperature and beyond without altering the atomic structure and would have a significant impact on emerging applications.