Bidirectional negative differential thermal resistance phenomenon and its physical mechanism in the Frenkel-Kontorova lattices

Thermal conduction of the Frenkel-Kontorova (FK) lattices with interfacial coupling is investigated numerically. The results indicate that: (i) For appropriate lattice periods, as the system is symmetric, a bidirectional negative differential thermal resistance (NDTR) phenomenon will appear. If the system is asymmetric, the bidirectional NDTR is gradually converted into an unidirectional NDTR. (ii) The bidirectional NDTR phenomenon effect also depends on the period of the FK lattice as the other parameters remains unchanged. With the increment of the lattice period, the bidirectional NDTR will gradually disappear. (iii) From a stochastic dynamics point of view, thermal transport properties of the system are determined by the competition between the two types of thermal conduction: one comes from the collusion between atoms, the other is due to the elastic coupling between atoms. For the smaller lattice periods, the former type of thermal conduction occupies the dominating position and the NDTR effect will appear.