Enhancing the ballistic thermal transport of silicene through smooth interface coupling

We have performed nonequilibrium molecular dynamics calculations on the length (L) dependence of thermal conductivity (Κ) of silicene both supported on and sandwiched between the smooth surfaces, i.e. h-BN, at room temperature. We find that Κ of silicene follows a power law Κ [proportional] L(β), with β increasing from about 0.3-0.4 under the effect of interface coupling, showing an enhancement of the ballistic thermal transport of silicene. We also find that β can be further increased to about 0.6 by increasing the interface coupling strength for the silicene sandwiched between h-BN. The increase of β for the supported case is found to come from the variation of the flexural acoustic (ZA) phonon mode and the first optical phonon mode induced by the substrate, whereas the unusual increase of β for the sandwiched case is attributed to the increment of velocities of all three acoustic phonon modes. These findings provide an interesting route for manipulating the ballistic energy flow in nanomaterials.