Anomalous heat conduction in asymmetric graphene Y junctions

• Heat pulse propagation in asymmetric graphene Y-junctions are investigated by MD simulation.
• Transmitted signal in the narrow branch is found to be stronger than that in the wide branch.
• The anomalous heat conduction could be attributed to the behavior of the longitude vibrational modes.

Through MD simulation of the transient heat pulse propagation in asymmetric Y junction, we report a novel type of controllable heat conduction in graphene nanostructure. The Y junction consists of a steam breaking into a wide branch and a narrow branch. In contrast to the classic situation where heat conductivity is proportional to the cross-sectional area of the material, the transmitted part of the heat pulse in the narrow branch is anomalously much stronger than that in the wide branch. As we increase the width ratio between the wide branch and narrow branch, transmitted coefficient in the narrow branch decreases a little, while in the wide branch, it decreases sharply. Specifically under 2:1 width ratio, transmitted coefficient of the narrow branch is three times that of the coefficient of the wide branch. Further analysis shows that the anomalous heat conduction is primarily induced by the behavior of the longitude vibrational modes.