Thermal switch and thermal rectification enabled by near-field radiative heat transfer between three slabs

In this paper, the near-field radiative heat flux of the system consisting of two SiO₂ plate sources and one 50 nm thick VO₂ film, a kind of insulator-metal transition material, placed between them is studied. The two sources are maintained at 400 and 300 K, respectively, and separated by a distance of 150 nm. By this configuration, the temperature of the film can be regulated by the control of the separation distance between the film and the sources via a piezoelectric motor. It is found that the net radiative heat flux of this system can be varied in a range of 7.5 × 10³-3.2 × 10⁴ W/m² for different position of the VO₂ film due to its phase transition. Hence, the functions of thermal switch and thermal rectification are able to be realized by this system. Particularly, the direction of the larger heat flux in the proposed thermal rectification can be reversed by changing the position of the VO₂ film. The effects of some parameters are investigated to improve the performance of the thermal rectification.