Consideration of enhancement of thermal rectification using metamaterial models

We present a systematic study to highlight some of the fundamental physics that governs metamaterial based electromagnetic thermal rectifiers. In such thermal rectifiers, the rectification arises from the alignment or misalignment of surface resonances in the forward or reverse scenarios, whereas the bulk states of metamaterials do not contribute to rectification. Therefore, we show that one can understand the behavior of such rectifiers by examining the relative excitation strength of the surface and bulk resonances. We verify such an understanding by accounting for the dependence of the contrast ratio on various parameters that define the dielectric response of the metamaterials.