Twist-angle-dependent thermal conduction in single-crystalline bilayer graphene

Thermal conductivity (κ) of the single-crystalline bilayer graphene (BLG) is investigated experimentally as a function of the interlayer twist angle (θ) and temperature using the optothermal Raman technique. The results show that a slight 2° twist angle leads to a κ decrease in 15% at ∼320 K. With the regulation of θ from 0° to 30°, the in-plane κ of the BLG decreases first and then increases showing an asymmetry V shape. The local maximum value of κ was reached when the twist angle is 30° and the highest value was found on the Bernal stacked BLG. The obtained κ is further found to be sensitive to the Moire periodicity but insensitive to the commensurate lattice constant of the twisted BLG. The non-equilibrium molecular dynamics simulation reveals that the twist angle in t-BLG affects the proportion of low-frequency phonons and finally changes the κ. The quantitative study validates the regulation of thermal conduction through the interlayer twist angle and favors the further understanding of thermal transport in the van der Waals bilayer systems.