Negative differential thermal resistance phenomenon in the FK-ϕ4 lattices

Abstract

Negative differential thermal resistance (NDTR) was investigated in a system consisting of two dissimilar anharmonic lattices exemplified by Frenkel–Kontorova (FK) lattices and ϕ4 lattices (FK-ϕ4). The results indicate that: (i) For appropriate periodic on-site potentials of FK lattice, as the system is asymmetric, an NDTR phenomenon will appear. (ii) The NDTR phenomenon also depends on the quartic on-site potentials of ϕ4 lattice as the other parameters remain unchanged. With the increment of the quartic on-site potential, the NDTR phenomenon will gradually disappear. (iii) As the system is asymmetric, the averaged environmental reference temperature and coupling displacement cannot only enhance NDTR phenomenon but also regulate thermal rectifier of the system as a thermal switch. (IV) Along with an increasing atomic number of the system, the NDTR phenomenon gradually disappears. Our results indicate that the on-site potential of nonlinear lattices plays a crucial role in the design of thermal devices.