Zhang Lenan, Zhong Yang, Li Xiangyu, Park Ji-Hoon, Song Qichen, Li Long, Guo Liang, Kong Jing, Chen Gang
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Nano Lett. 2023 Sep 13;23(17):7790-7796. doi: 10.1021/acs.nanolett.3c01050. Epub 2023 Aug 28.
Advances in two-dimensional (2D) devices require innovative approaches for manipulating transport properties. Analogous to the electrical and optical responses, it has been predicted that thermal transport across 2D materials can have a similar strong twist-angle dependence. Here, we report experimental evidence deviating from this understanding. In contrast to the large tunability in electrical transport, we measured an unexpected weak twist-angle dependence of interfacial thermal transport in MoS bilayers, which is consistent with theoretical calculations. More notably, we confirmed the existence of distinct regimes with weak and strong twist-angle dependencies for thermal transport, where, for example, a much stronger change with twist angles is expected for graphene bilayers. With atomic simulations, the distinct twist-angle effects on different 2D materials are explained by the suppression of long-wavelength phonons via the moiré superlattice. These findings elucidate the unique feature of 2D thermal transport and enable a new design space for engineering thermal devices.
二维（2D）器件的进展需要创新方法来操控输运特性。类似于电学和光学响应，据预测，二维材料中的热输运可能具有类似的强烈扭转角依赖性。在此，我们报告了与这种认识相悖的实验证据。与电输运中的大可调性相反，我们测量到二硫化钼双层膜中界面热输运的扭转角依赖性出人意料地弱，这与理论计算结果一致。更值得注意的是，我们证实了热输运存在扭转角依赖性强弱不同的不同区域，例如，预计石墨烯双层膜随扭转角的变化要强得多。通过原子模拟，不同二维材料上独特的扭转角效应可通过莫尔超晶格对长波声子的抑制来解释。这些发现阐明了二维热输运的独特特性，并为热器件工程开辟了新的设计空间。
