Origin of negative differential thermal resistance in a chain of two weakly coupled nonlinear lattices

摘要

Negative differential resistance in electronic conduction has beenextensively studied, but it is not the case for its thermal counterpart,namely, negative differential thermal resistance (NDTR). We present a classicalLandauer formula in which the nonlinearity is incorporated by theself-consistent phonon theory in order to study the heat flux across a chainconsisting of two weakly coupled lattices. Two typical nonlinear models of hardand soft on-site potentials are discussed, respectively. It is shown that thenonlinearity has strong impacts on the occurring of NDTR. As a result, atransition from the absence to the presence of NDTR is observed. The origin ofNDTR consists in the competition between the temperature difference, which actsas an external field, and the temperature-dependent thermal boundaryconductance. Finally, the onset of the transition is clearly illustrated forthis model. Our analytical calculation agrees reasonably well with numericalsimulations.