Li Hongyang, Ying Hao, Chen Xiangping, Nika Denis L, Cocemasov Alexandr I, Cai Weiwei, Balandin Alexander A, Chen Shanshan
Department of Physics, Laboratory of Nanoscale Condense Matter Physics and State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, 361005 China.
Nanoscale. 2014 Nov 21;6(22):13402-8. doi: 10.1039/c4nr04455j.
We have investigated experimentally the thermal conductivity of suspended twisted bilayer graphene. The measurements were performed using an optothermal Raman technique. It was found that the thermal conductivity of twisted bilayer graphene is lower than that of monolayer graphene and the reference, Bernal stacked bilayer graphene in the entire temperature range examined (∼300-700 K). This finding indicates that the heat carriers - phonons - in twisted bilayer graphene do not behave in the same manner as that observed in individual graphene layers. The decrease in the thermal conductivity found in twisted bilayer graphene was explained by the modification of the Brillouin zone due to plane rotation and the emergence of numerous folded phonon branches that enhance the phonon Umklapp and normal scattering. The results obtained are important for understanding thermal transport in two-dimensional systems.
我们通过实验研究了悬浮扭曲双层石墨烯的热导率。测量是使用光热拉曼技术进行的。结果发现，在整个考察的温度范围（约300 - 700 K）内，扭曲双层石墨烯的热导率低于单层石墨烯以及参考的伯纳尔堆叠双层石墨烯。这一发现表明，扭曲双层石墨烯中的热载流子——声子——的行为方式与在单个石墨烯层中观察到的不同。扭曲双层石墨烯中热导率的降低是由于平面旋转导致布里渊区的改变以及大量折叠声子分支的出现，这些分支增强了声子的倒逆散射和正常散射。所获得的结果对于理解二维系统中的热输运具有重要意义。
