An important mechanism for thermal rectification in graded nanowires
YY Liu and WX Zhou and LM Tang and KQ Chen, APPLIED PHYSICS LETTERS, 105, 203111 (2014).
In the quest for the origin of the different thermal rectifying behavior of two graded nanowires, we reveal the important role that standing waves play in the thermal transport properties of such graded structures. Evidence for the existence of standing waves is given from two angles, and one possible scenario of the origin of the standing wave is presented. The key point is that the formation of the standing wave, which greatly hinders the propagation of phonon waves, occurs only when the narrow end of the nanowire is at a higher temperature than the wide end, making the heat current flow preferably from the wide end to the narrow end. (C) 2014 AIP Publishing LLC.
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