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

Thermal conductivity (kappa) of the single-crystalline bilayer graphene (BLG) is investigated experimentally as a function of the interlayer twist angle (theta) and temperature using the optothermal Raman technique. The results show that a slight 2 degrees twist angle leads to a kappa decrease in 15% at similar to 320 K. With the regulation of theta from 0 degrees to 30 degrees, the in-plane kappa of the BLG decreases first and then increases showing an asymmetry V shape. The local maximum value of kappa was reached when the twist angle is 30 degrees and the highest value was found on the Bernal stacked BLG. The obtained kappa 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 kappa. 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.

Automated summary

This study experimentally investigates the thermal conductivity of single-crystalline bilayer graphene as a function of interlayer twist angle and temperature. The results show that a slight twist angle can lead to a significant decrease in thermal conductivity. The study reveals the sensitivity of thermal conduction to the twist angle, providing insights into thermal transport in van der Waals bilayer systems.