Thermal Conductivity of Small Angle Twisted Bilayer Graphene

The effect of misorientation on the in-plane thermal conductivity of twisted BLG (TBG) is still poorly understood. The one experimental study found that interlayer misorientation could reduce the in-plane thermal conductivity by 50%. A recent theoretical study of TBG with the three smallest commensurate unit cells, 21.8^o, 32.2^o, and 13.2^o, found that the thermal conductivity decreased approximately linearly as the commensurate lattice constant increased. What happens at smaller misorientation angles of 10^o or less is still an open question. For this range of rotation angles, we perform large-scale, non-equilibrium molecular dynamics calculations of the thermal conductivity of TBG for twist angles down to 1.89^o. The picture that emerges from this study is that the misorientation reduces the shear elastic constant C44 which increases the wrinkling of the TBG. The increased out-of-plane wrinkling then reduces the thermal conductivity.