Path-dependent bifunctional device in thermal-electric field

Abstract

Janus metamaterial refers to a kind of artificial device that can exhibit different functions along different paths. Compared with the existing metamaterial only possessing the single omnidirectional or unidirectional function, we propose a path-dependent bifunctional device in a thermal-electric field, which can present two distinct thermal and electric behaviors (concentrating and cloaking) under different directions of heat flux and electric current. We theoretically derive the anisotropic material parameters of the ideal Janus device to achieve the path-dependent functionalities based on the successive transformation method. Then, in order to realize the engineering applications of the Janus device, the effective medium theory is employed to eliminate the anisotropy of the material parameters using the multilayered structure, thus avoiding extreme material parameters. We further analyze the path-dependent manipulation effects of the coupled thermal and electric fields. The numerical simulations are carried out to demonstrate the performances of ideal or multilayered Janus devices under different physical conditions. The results show that the performances of the multilayered Janus device coincide with those of the ideal Janus device, and these different Janus devices can perfectly achieve the concentrating function along the x-axis and the cloaking function along the y-axis in different thermal and electric fields simultaneously. It is anticipated that the path-dependent effect of the Janus metamaterial can also be extended to other multi-physical fields with different directional functions.